bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the mechanical behaviour of reclaimed asphalt aggregates without binder addition
Authors: Gaillard Laura , Chazallon Cyrille , Hornych Pierre , Quezada Juan Carlos
Published: June 2019

The objective of this paper is to investigate a source of reclaimed asphalt aggregates without binder addition. To this end, a series of triaxial tests was performed. First, monotonic triaxial tests allowed to determine failure resistance of the material at 20°C, 50°C and at 20°C with a prior preheating at 50°C. Then, the resilient and permanent behaviours at 20°C were studied thanks to Repeated Load Triaxial (RLT) tests with different levels of loading. The results show that increasing the temperature test implies a drop of failure resistance but a higher cohesion. RLT tests reveal a stress dependent resilient behaviour. Finally, the experimental results were compared with calibrations of the non-linear elastic Boyce model.
Experimental and analytical investigations of volume change behaviour of saturated expansive soils in oedometer test
Authors: Hiraga Misa , Kyokawa Hiroyuki , Koseki Junichi
Published: June 2019

The chemical and mechanical behaviours of saturated bentonite were experimentally and analytically investigated. A series of oedometer tests on saturated bentonite was conducted. By replacing the cell fluid during the oedometer test, one-dimensional osmotic consolidation and swelling behaviour were observed. The experimental results were simulated numerically using a constitutive model by considering the influence of electrochemical phenomena of clay mineral crystals on the macrostructural behaviour. It was concluded that the typical mechanical swellability of water-saturated bentonite in oedometer test is affected by a positive dilatancy behaviour due to the lower shear strength. After the osmotic consolidation test, a lateral contraction of the specimen in the oedometer was observed; this affected the compressibility during the subsequent mechanical consolidation. It was also concluded that the concentration of Na+ in the pore fluid affects the specific mechanical properties of bentonite.
Stabilization and recycling of contaminated marine sediments
Authors: Todaro Francesco , Vitone Claudia , Notarnicola Michele
Published: June 2019

The paper deals with the treatment and reuse of submarine sediments, i.e. a relevant environmental issue due to the annual huge quantities of dredged sediments (over half contaminated) in Europe. In a vision of sustainability and circular economy, stabilization and solidification (S/S) treatments represent an interesting solution for both environmental protection and reuse of sediments in engineering works. The investigation involved polluted clayey sediments taken up to depths of about 1.5m from the seafloor of the Gulf of Taranto (South of Italy). The research investigates the effects of a treatment with cement and lime enhanced by the addition of green additives, such as active carbon and biochar, for chemical remediation. The last one is a promising and cheap adsorbent material, that is the by-product of - mainly - agricultural waste pyrolysis. The first results suggest that appropriate mix designs and curing times could allow the reuse of sediments by both improving their geotechnical characteristics and making them environmentally acceptable in accordance to end-of-waste criteria.
Yielding behaviour of cemented binary mixture
Authors: Subramanian Sathya , Ku Taeseo
Published: June 2019

Cement stabilization is commonly used for improving soft soils and the mechanical behaviour of cemented pure clay has been well documented. However, limited studies have investigated the effect of sand in a cement-clay matrix because the conventional water to solid (solid includes soil and cement) ratio cannot be simply used to characterize the behaviour of cemented binary mixture. The water holding capacity of the mixture reduces with increase in sand content, when the water to solid ratio is kept constant. In this study, the ratio of water to clay and cement is kept constant, so that the effect of sand content could be studied. The materials used in this study are kaolin clay, sand with D50 of 0.71 mm and Ordinary Portland cement type 1. Sand content varies from 0% to 50% and curing time is kept constant at 7 days. We used three ratios of water to clay and cement which correspond to 139%, 104% and 78%. The isotropic yield point increases with increase in sand content and cement content, while it reduces with increase in water content. A power function captures the variation of yield point with the ratio of water to cement and clay.
Study on progression of deterioration in improved surplus soils
Authors: Sanjeewani Dayani , Miyashita Yukika , Kuwano Reiko , Negishi Atsunori
Published: June 2019

This study investigated the progression of deterioration in cement treated surplus soils with cement contents of 1.7, 3.5 and 5.3 % under soaked condition by conducting needle penetration test and measuring calcium ion distribution within soil specimens. It was found that deterioration has progressed throughout the specimen after 336 days soaking in all the cases. From the measurement of calcium ion distribution, it was identified that calcium has leached out from the centre to the surface of the specimens though that distribution did not follow a good correlation with localized strength distribution. It was understood that the progression of deterioration of improved surplus soils with lower cement contents cannot be explained only with the remaining amount of calcium.
Measuring shear strength parameters of polymer-added bentonite-sand mixtures in laboratory experiments
Authors: Ozhan Hakki O.
Published: June 2019

In order to evaluate the shear strength parameters of an anionic polymer-added bentonite-sand mixture that was permeated with tap water, Proctor compaction tests and direct shear tests were performed on the mixture with a bentonite content of 15% by mass. The polymer content in the polymer-bentonite mixture was chosen as 0.5, 1, 2, 5, 10, 15 and 20% by mass, respectively. According to the results, maximum dry unit weight (Vdmax) first decreased as the polymer content was increased to 1% and then, increased. Vdmax of 20% polymer-added mixture and the mixture without polymer addition was measured as 17.55 and 17.28 kN/m3, respectively. Test results indicated that cohesion (c) increased and internal friction angle (ø) decreased due to polymer addition. 2% polymer addition caused an increase of 42 kPa in c but a decrease of 4.2° in ø. As the polymer content increased, maximum shear strength of the mixture (τmax) increased. τmax increased from 171.8 to 197.8 kPa as the polymer content was increased from 0 to 2%. As a result, 2% anionic polymer-added bentonite-sand mixture provided sufficient increase in the shear strength of the mixture.
Uprooting of tree induced by typhoon: a case study of super typhoon Mangkhut in university town of Shenzhen
Authors: Huang Junwen , Su Yan , Zhu Guanyu , Chen Rui , Wu Xiaofeng
Published: June 2019

Super typhoon Mangkhut resulted a large number of fallen tree in form of uprooting in university town of Shenzhen (UTSZ), which hadn't happened for years. This study conducted a survey about tree uprooting induced by super typhoon Mangkhut in UTSZ, aiming to reveal main reasons for tree uprooting in UTSZ. Species of fallen trees were recognized. Fallen direction and height of fallen tree were measured. Also depth and diameter of root-soil plate and dry density of soil beneath root-soil plate were measured. The results showed that many fallen trees with uprooting in UTSZ had relatively small volume of root-soil plate which was not able to offer sufficient anchorage to tree during typhoon. One of solutions to avoid this phenomenon is not to select tree species with shallow root depth. Ponding was found in many places where uprooting occurred in UTSZ. Increase of degree of saturation of soil induced by ponding can significantly decrease soil strength which is a major component of anchorage of tree. Thus we recommend to modify the poor drainage condition of soil in UTSZ. Degree of compaction of soil may not be a main factor related to tree uprooting in UTSZ.
Direct interface shear tests on Dunkirk sand
Authors: Salama Imane , Dano Christophe
Published: June 2019

After a field test campaign conducted in Dunkirk (north of France) on open-ended steel piles aiming to study the ageing phenomenon, laboratory scale shear tests were designed to study the behaviour of the sand-steel interface. In order to carry out this laboratory investigation, the direct interface shear apparatus was used for characterizing Dunkirk sand (in dry or unsaturated conditions with about 6% water content as in the field) consolidated on initially smooth mild steel plates at different consolidation time intervals (0, 1 and 7 days) and different consolidation stresses (50, 100, 200 and 300 kPa). The test program also included two normal boundary conditions (Constant normal load CNL and constant volume CV) so that they can be compared to the field results and determine the most approaching configuration. More, the unsaturated condition induced a corrosion of the mild steel plates, causing a layer of sand remaining glued to the plate after removing the shear box. Traces of corrosion were also observed on the lower part of the sand samples (in contact with the plate). These observations lead to the interpretation of an increase of the mechanical properties (local cohesion and increase of the friction angle). In order to follow the evolution of the corrosion for each plate, thickness measurements of the sand layer stuck on the plates were carried out.
Strength anisotropy at soil-structure interfaces with snake skin inspired structural surfaces
Authors: Stutz Hans Henning , Martinez Alejandro , Heepe Lars , Tram Tramsen Halvor , Gorb Stanislav N.
Published: June 2019

Typical soil-structure interfaces exhibit a response that is independent of loading direction due to the symmetry of the surfaces' profile. This study presents results from an experimental investigation on the response of sand specimens sheared against three types of surfaces bio-inspired from the skin along the underside of snakes. The results of shear box interface shear tests indicate that all three surfaces exhibit significant anisotropy in response in terms of mobilized shear resistances and corresponding volumetric changes. A discussion on the practical implications and potential benefits of implementation of the snake skin-inspired surfaces in engineering design is provided.
Characterization of peak shear strength of rough rock joints using limited displacement multi-stage direct shear (LDMDS) tests
Authors: MacLaughlin Mary , Berry Steve , Petro Michael , Berry Katherine , Bro Anders
Published: June 2019

Current standard direct shear test methods for rock joints do not account for damage to the specimens' asperity profiles; tests require shearing of a single specimen to large displacements under successive normal stresses (the multistage test), or the use of similar specimens in multiple tests. Due to the inherently unique nature of rock joints and corresponding difficulty in obtaining specimens with identical or even similar geometries, multistage tests are more common. A major issue with the multistage test is that successive shearing of the specimen damages the surface asperities and changes its overall roughness profile, reducing the peak shear stress and consequently resulting in underestimation of the friction angle and overestimation of the joint shear intercept (cohesion). The limited displacement multistage direct shear (LDMDS) test method minimizes these testing imperfections by allowing shearing of a single specimen without extensive asperity damage, accomplished by immediately pausing shear displacement once peak shear stress has been reached, then proceeding to shear the specimen under the following normal stress value, and shearing into the post-peak region only after identifying multiple values of peak shear strength. The authors have validated the LDMDS procedure using cement replicates of rock joints, demonstrating that it yields more accurate strength parameters than the standard multistage direct shear test.
Design of crushable particles in DEM based on single grain compression
Authors: Tedesco Bruna , Cordão Neto Manoel Porfirio , Tarantino Alessandro , Farias Márcio
Published: June 2019

Grain crushing controls the response in shear of granular materials and has an impact on the collapse mechanism of geo-structures. To simulate the effects of grain crushing on the macroscopic response, the Discrete Element Method (DEM) appears to be a viable option considering its proven capability of capturing key aspects of the response of granular materials. One of the approaches to simulate particle crushing via DEM consists in creating a particle by assembling smaller sub-particles ‘bonded’ together by adhesion forces. When the force at the contact between two sub-particles exceeds the adhesion, the bonding is broken irreversibly. A critical aspect in this approach is the characterization of i) the ‘random’ distribution of the adhesion between the sub-particles, and ii) the initial rotation angle of the particles being assembled initially. The tensile strength of a single grain, as measured experimentally by diametral compression between flat platens, typically follows the Weibull distribution. This is proposed to be the criterion to validate any probabilistic distribution selected for the adhesion and the initial rotation angle. The effect of a normal distribution of adhesion and initial rotation on compressive strength was investigated by compressing either a regular ‘cylindrical’ particle or an irregular particle. It is shown that a normal probabilistic distribution of both the adhesion and the rotation angle returns a Weibull distribution of the compressive strength. It is also shown that the rotation angle plays a very critical role and this should be taken into account when initially assembling the ‘crushable’ particles. The rotation angle relocates the contact points, which in turn control the stress at which the particle breaks.
Seismic behaviour of a large-scale concrete-block retaining wall
Authors: Sato Noboru , Sawamatsu Toshikazu , Nitta Takehiko , Miyatake Hiroaki , Kondo Kazuhito
Published: June 2019

In this study, an inclined model experiment and finite element analyses were conducted to evaluate the failure mode and seismic response of a dry-type large-scale concrete-block retaining wall (LCBW). In the experiment, the objective was to reproduce the sliding between concrete blocks that was observed in past cases LCBW damage in order to characterise the behaviour until failure. A numerical simulation corresponding to the experimental conditions was conducted by the finite element method (FEM). Dynamic analyses were also performed by FEM to investigate the seismic response of the concrete blocks under various ground conditions. The experimental results revealed that slip between the concrete blocks caused brittle failure of the LCBW. In the FEM simulation, the joint elements reproduced the experimentally observed sliding between the concrete blocks. A dynamic simulation of the full-scale model revealed that significant sliding and rocking of the concrete block occur in a dry-type LCBW. These findings indicate that stress concentration may occur at the heels of the concrete blocks during an earthquake.
Design of plate and screw anchors in dense sand: failure mechanism, capacity and deformation
Authors: Cerfontaine Benjamin , Knappett Jonathan , Brown Michael , Bradshaw Aaron
Published: June 2019

Plate and screw anchors provide a significant uplift capacity and have multiple applications in both onshore and offshore geotechnical engineering. Uplift design methods are mostly based on semi-empirical approaches assuming a failure mechanism, a normal and a shear stress distribution at failure and empirical factors back-calculated against experimental data. However, these design methods are shown to under- or overpredict most of the existing larger scale experimental tests. Numerical FE simulations are undertaken to provide new insight into the failure mechanism and stress distribution which should be considered in anchor design in dense sand. Results show that a conical shallow wedge whose inclination to the vertical direction is equal to the dilation angle is a good approximation of the failure mechanism in sand. This shallow mechanism has been observed in each case for relative embedment ratios (depth/diameter) ranging from 1 to 9. However, the stress distribution varies non-linearly with depth, due to the soil deformability and progressive failure. A sharp peak of normal and shear stress can be identified close to the anchor edge, before a gradual decrease with increasing distance along the shear plane. The peak stress magnitude increases almost linearly with embedment depth at larger relative embedment ratios. Although further research is necessary, these results lay the basis for the development of a new generation of design criteria for determining anchor capacity at the ultimate limiting state.
Elasto-plastic analysis of a multi-stage excavation in bonded geomaterials
Authors: Moghaddasi Hamed , Khoshghalb Arman
Published: June 2019

The deformation characteristics of braced and unbraced excavations in a dry structured soil are investigated numerically. A constitutive model based on the theory of bounding surface plasticity is used to predict the plastic deformation of the soil. A plastic cementation index is introduced in the hardening modules to capture soil degradation. In the model, the progress of the degradation is associated with the stress magnitude and the accumulated plastic deformation. The constitutive model is implemented in a finite difference code to analyse the lateral deformation of braced and unbraced excavations. The implemented model captures the strength increase of soils due to cementation, and predicts the subsequent debonding and strength degradation due to excavation. It is shown that soil cementation significantly influences the compression and tensile strengths of soils, and alters the deformation profile of the excavated face.
Geotechnical risk analyses and evaluation of design criteria of embankment dam systems
Authors: Marquez Hector , Kamalzare Mehrad
Published: June 2019

The integrity of the state and national system of embankment dams and levees is a crucial component in ensuring the safety of protected communities in any country. The failure of such systems due to natural or man-made hazards can have monumental repercussions, sometimes with dramatic and unanticipated consequences on human life, property and the economy of the states and the country. For highly seismic areas such as Southern California, it is critical to investigate and study the seismic response of embankment dams and levees for the afore mentioned reasons. While experimental studies of embankment dams under seismic loads is expensive, very time consuming, and limited, numerical studies usually suffer from lack of legitimate real data for verification of the developed models. However, organizations such as the California Strong Motion Instrumentation Program (CSMIP) instrument lifeline structures such as earth dams and levees with accelerometers and actively collect strong-motion data. The data obtained from CSMIP accelerometers is then processed by the Center for Engineering Strong Motion Data (CESMD) and made public for earthquake engineering applications. In this study, numerical models of existing earth embankment dams verified with site specific CESMD data are created in order to analyze their stability for a future earthquake, for post-earthquake response purposes. The seismic fragility of the modelled dams was assessed, providing insight for decision makers regarding priority areas important for matters such as maintenance, dam retrofit, or first-aid response locations for a hypothetical major earthquake. Society can benefit from increased awareness of the seismic response of the modelled structures and can be better prepared for a potential catastrophic seismic event.
Effects of grout injection techniques in pressure grouted soil nail system
Authors: Zahidul I. Bhuiyan Mohammad , Wang Shanyong , Sloan Scott W. , Carter John , Mahzabeen Raka Tabassum
Published: June 2019

The use of pressure grouting techniques in the soil reinforcement system is frequent as it has many advantages over gravity grouting. Pressure grouting can be injected by pressure and volume (flow) controlled techniques. A preliminary study was conducted for a newly developed pressure grouted soil-nail system, where a latex membrane was used as a liner around the grouting outlet to form a Tube a Manchette (TAM) for direct injection of grout into sand. In addition, a grout bag was formed with the membrane to prevent the grout injection into the sand for simulating a compaction grouting. In the investigation, a newly developed volume controlled injection system was used to inject the cement grout into the sand or grout bag for a specified flow rate and the interaction of injected grouted with the soil mass (i.e., soil stress state) was monitored by the installed total earth pressure cell around the grout outlets. From the investigation, it was found that the injected grout volume was much less for the soil-nail (TAM) than that with a grout bag around for a certain flow rate. In addition, the preliminary results indicated that the pullout capacity of the pressure grouted soil-nail controlled by the injected grout volume (grout bulb).
A method for predicting the influence of matric suction changes on CPT tip resistance
Authors: Miller Gerald A. , Collins Rodney W.
Published: June 2019

The Cone Penetration Test (CPT) is a valuable tool for continuous soil profiling and estimating soil properties. A CPT sounding will often pass through the active zone of an unsaturated soil profile, near the ground surface where moisture conditions and matric suction can vary considerably with depth and time. For many projects, the active zone is also significant to the support of shallow foundations and overlying embankments. However, the strength and stiffness of the unsaturated soils in this zone can be significantly affected by variations in the moisture content and matric suction. Likewise, the cone penetration tip resistance and sleeve friction will be influenced by the variations in moisture conditions and suction. Therefore, it is important to consider the soil moisture conditions when CPTs are conducted relative to the moisture conditions assumed for geotechnical design. This paper presents a method for predicting changes in tip resistance as result of changes in matric suction. The method extends the bearing capacity theory to predict changes in cone tip resistance due to changes in matric suction. CPT data collected at test sites, during wet and dry seasons and representing different soil types, are presented to demonstrate the viability of the proposed method.
Importance of coherence between geophysical and geotechnical data in dynamic response analysis
Authors: Karray Mourad , Tremblay Simon-Pierre , Hussein Mahmoud N. , Chekired Mohamed
Published: June 2019

The demand for a precise evaluation of shear wave velocity Vs, is gaining interest in the field of geotechnical engineering due to its importance as a key parameter required to properly evaluate typical characteristics of soils. Nowadays, Vsmeasurements are performed on the field using different methods, such as SCPT tests and various geophysical methods. However, the effectiveness of these field measurements is not guaranteed and rather depends on how they are analyzed. Furthermore, a proper analysis is critical since the collected data may be used in liquefaction evaluation or earthquake ground response analyses. In these situations, it is recommended to verify the coherence between the obtained geophysical (Vs) and geotechnical (N-SPT, qc-CPT) measurements using alternative methods (e.g., Vs-correlations, H/V method, etc...). In some situations, the correlation between the different measurements makes it easier to unambiguously define seismic wave profiles. In other cases, geophysical and geotechnical tests would provide different resolutions for Vsmeasurements, an issue that complicates the decision of the practitioner. In this paper, we first demonstrate the importance of the shear-wave velocity in liquefaction potential analysis. A case study performed in eastern Canada is also presented where we show the importance of the method used to calculate Vsprofiles (MASW, MMASW).
Systematic slope stability assessment through deformation field monitoring
Authors: Wei Yukun , Lundberg Anders B. , Resare Fredrik
Published: June 2019

Field monitoring is frequently carried out during excavations and other geotechnical activities and provides additional information during the execution of a construction project. The interpretation of field monitoring data is often obscured by measurement noise and disturbance, and a systematic approach to assess both the quality and implications of the field monitoring data is very helpful in geotechnical practice. The possibility to infer practical conclusions from the field monitoring data depends on the type of field measurements, especially in monitoring of the stability of slopes. Pore pressure measurements can serve as a direct measurement of utilized soil strength for a slope, while deformation measurements are significantly more ambiguous and complicates the interpretation. The assessment of slope stability through field monitoring of deformations requires inverse or back analysis of the soil properties, followed by a forward analysis of the resulting slope stability. Such an inverse or back analysis is frequently influenced by non-uniqueness of the material properties and the stability of the measurement data. Systematic approaches to inverse or back analysis have been demonstrated in the scientific literature, but the practical use of these methods is not entirely straight-forward. The current paper presents a case study of systematic slope stability assessment through field measurements of deformations with a review of the field monitoring programme, numerical simulations of deformations, and a simplified approach to back analysis of the soil parameters. The excavation of a slope in an urban environment including layers of organic clay covered with highly heterogeneous gravel fill is used as an example of geotechnical back analysis. The aim is to elucidate some of the challenges in geotechnical back analysis while providing some practical solutions for practice.
Acoustic emission instrumentation method for slope monitoring
Authors: Caicedo Bernardo , Patino-Ramirez Fernando
Published: June 2019

Applications using acoustic emission techniques have shown promising results for slope monitoring. This study proposes a modified active waveguide slope monitoring device with AE measurement at either end of the device which is capable of calculating deformation profiles in real time besides its common use as an alarm method. The coupled calibration methodology allows the location of the slip surface and quantification of slope displacement accounting for the efficiency of the sensors and for attenuation due to distance between an event and the sensors. An analysis software is presented too, in order to propose the algorithms necessary to quantify deformation profiles in real time. The present study proposed some guidelines to perform further field testing based on the procedures and analysis algorithms proposed that showed promising laboratory results.
A Peccati-Tudor type theorem for Rademacher chaoses
Authors: Zheng Guangqu
Published: June 2019

In this article, we prove that in the Rademacher setting, a random vector with chaotic components is close in distribution to a centered Gaussian vector, if both themaximal influenceof the associated kernel and the fourth cumulant of each component is small. In particular, we recover the univariate case recently established in Döbler and Krokowski (2019). Our main strategy consists in a novel adaption of the exchangeable pairs couplings initiated in Nourdin and Zheng (2017), as well as its combination with estimatesviachaos decomposition.
Evidence for Involvement of TRPV1 Receptors and Potassium Channels in the Seizures Induced by α-Sanshool
Authors: Reyes-Trejo Benito , Morales-Hernández Mario Noel , González-Anduaga Gloria Melisa , Balderas-López José Luis , Tavares-Carvalho José Carlos , Navarrete Andrés
Published: June 2019

α-Sanshool is an alkamide isolated from the stem bark of Zanthoxylum liebmannianum, a Mexican medicinal plant known as Colopahtle. Our research group has reported that the intraperitoneal administration of α-sanshool induces tonic-clonic seizures in mice. In the present study, we investigated the convulsive effect of this alkamide and elucidated its mechanism of action by comparing with well-known convulsive and anticonvulsive drugs in an in vivo approach. α-Sanshool showed a potent (ED50 [CL 95%]=3.06 [2.92–3.22] mg/kg) and immediate (2±2 s) seizure effect after the intraperitoneal administration in mice. The convulsive effect of this alkamide was only observed for intraperitoneal administration; the oral route did not show any effect. α-Sanshool was less potent than strychnine (ED50 [CL 95%]=1.53 [1.44–1.62] mg/kg), but more effective than bicuculline, 4-aminopyridine, affinin, and pentylenetetrazol, in that order. The seizures induced by α-sanshool were reduced by capsazepine and diazoxide, suggesting the involvement of TRPV1 and potassium channels in the mechanism of action of this compound.
Eine Frage des Standpunktes
Authors: Wildner Manfred
Published: June 2019

„Gib mir einen Punkt, wo ich hintreten kann und ich bewege die Erde“ – so lautet ein dem griechischen Mathematiker, Physiker und Ingenieur Archimedes im Zusammenhang mit dem Hebelgesetz zugeschriebener Satz 1. Als „archimedischen Punkt“ bezeichnen wir seither auch viel allgemeiner einen festen Punkt, wie z. B. eine offensichtliche, unbezweifelbare Wahrheit in einer Argumentation. Auch wenn wir im Gesundheitswesen nicht unbedingt die Welt aus den Angeln heben wollen, so ist doch eine gute Ortskenntnis, im Sinne eines guten Verständnisses der Gegebenheiten, Zuständigkeiten und Regularien, ebenfalls von großer Bedeutung.
An Example of Ketone Olefination via Praseodymium-Mediated Barbier Reaction in the Presence of Diethyl Phosphite
Authors: Cao Xu yan , Huang Fei , Zhang Songlin
Published: June 2019

The first example of carbon double-bond formation via praseodymium-mediated Barbier type reaction of ketones and allyl halides in the presence of diethyl phosphite is reported. The reaction is highly α-regioselective and conveniently carried out under mild conditions in a one-pot fashion. From a synthetic point of view, a series of conjugated alkenes were obtained in moderate to good yields in this one-pot reaction with practical reaction conditions.
Resistivity scaling and electron surface scattering in epitaxial Co(0001) layers
Authors: Milosevic Erik , Kerdsongpanya Sit , McGahay Mary E. , Zangiabadi Amirali , Barmak Katayun , Gall Daniel
Published: June 2019

In situ and ex situ transport measurements on epitaxial Co(0001)/Al2O3(0001) layers with thickness d = 7–300 nm are used to quantify the resistivity ρ scaling due to electron surface scattering. Sputter deposition at 300 °C followed by in situ annealing at 500 °C leads to single-crystal layers with smooth surfaces (<1 nm roughness) and an epitaxial relationship: Co[0001]‖Al2O3[0001] and Co[101¯0]‖Al2O3[112¯0]. The measured ρ vs d data are well described by the classical expression by Fuchs and Sondheimer at both 295 and 77 K, yielding a temperature-independent product of the bulk resistivity times the mean free path ρo × λ and an effective room temperature λ = 19.5 ± 1.0 nm. The resistivity increases by 9%–24% upon air exposure for layers with d ≤ 21 nm, indicating a transition from partially specular (p = 0.55 ± 0.05) to completely diffuse (p = 0) surface scattering during native oxide formation. The overall results suggest that Co exhibits a resistivity scaling that is comparable to W and approximately 2× smaller than that of Cu and that the resistance of narrow Co lines can be reduced considerably by engineering the Co-liner interface to facilitate specular electron scattering.
A time- and angle-resolved photoemission spectroscopy with probe photon energy up to 6.7 eV
Authors: Yang Yuanyuan , Tang Tianwei , Duan Shaofeng , Zhou Chaocheng , Hao Duxing , Zhang Wentao
Published: June 2019

We present the development of a time- and angle-resolved photoemission spectroscopy based on a Yb-based femtosecond laser and a hemispherical electron analyzer. The energy of the pump photon is tunable between 1.4 and 1.9 eV, and the pulse duration is around 30 fs. We use a KBe2BO3F2 nonlinear optical crystal to generate probe pulses, of which the photon energy is up to 6.7 eV, and obtain an overall time resolution of 1 ps and energy resolution of 18 meV. In addition, β-BaB2O4 crystals are used to generate alternative probe pulses at 6.05 eV, giving an overall time resolution of 130 fs and energy resolution of 19 meV. We illustrate the performance of the system with representative data on several samples (Bi2Se3, YbCd2Sb2, and FeSe).
Dynamic qualitative bolt force measurements for investigating influence factors on the pushout effect of small calibre ammunition
Authors: Muster Michael , Hameed Amer , Wood David
Published: June 2019

A small calibre weapon system consists of the weapon and the ammunition. In the case of bolt action rifles during the process of firing, the breech is a rigid bearing which prevents the casing from being pushed out. However, not the whole pushout force is taken by the bolt. Due to friction forces at the casing boundary, the chamber of the weapon can absorb a significant part of the pushout force. The duration of the pushout force is in the order of milliseconds. Piezoelectric strain gauges are capable of recording such short time events qualitatively. To increase the measurability of force obtained from raw signal, is filtered using a bandpass filter and applying a signal envelope. The results from the strain gauges are verified by a piezoelectric force washer. In this paper, two different lubrication states and two different casing materials are analysed to evaluate their influences on the force absorbed by the bolt. The analysis indicated that lubricated casings lead to bolt forces which are more than three times higher when compared unlubricated casings. The unlubricated steel casing also showed a significant lower bolt force when compared with the regular brass casing. However, this effect is reversed, if the casing is lubricated. This work demonstrates how to measure highly dynamic events. The acquired results can be directly applied to 5.56x45 bolt action rifles. These measurements may also have a significant influence on self-loading rifles, since the process of reloading is also dependent on the pushout force. The general application area is target competitive shooting and military purposes.
Two-dimensional magnetohydrodynamic turbulence with large and small energy-injection length scales
Authors: Banerjee Debarghya , Pandit Rahul
Published: June 2019

Two-dimensional magnetohydrodynamics, forced at (a) large length scales or (b) small length scales, display turbulent, but statistically steady, states with widely different statistical properties. We present a systematic, comparative study of these two cases (a) and (b) by using direct numerical simulations. We find that, in case (a), there is energy equipartition between the magnetic and velocity fields, whereas, in case (b), such equipartition does not exist. By computing various probability distribution functions, we show that case (a) displays extreme events that are much less common in case (b).
Giant reversible barocaloric response of (MnNiSi)1−x(FeCoGe)x (x = 0.39, 0.40, 0.41)
Authors: Lloveras Pol , Samanta Tapas , Barrio María , Dubenko Igor , Ali Naushad , Tamarit Josep-Lluís , Stadler Shane
Published: June 2019

MnNiSi-based alloys and isostructural systems have traditionally demonstrated impressive magnetocaloric properties near room temperature associated with a highly tunable first-order magnetostructural transition that involves large latent heat. However, these materials are limited by a small field-sensitivity of the transition, preventing significant reversible effects usable for cooling applications. Instead, the concomitant large transition volume changes prompt a high pressure-sensitivity, and therefore, promise substantial barocaloric performances, but they have been sparsely studied in these materials. Here, we study the barocaloric response in a series of composition-related (MnNiSi)1−x(FeCoGe)x (x = 0.39, 0.40, 0.41) alloys that span continuously over a wide temperature range around ambient. We report on giant reversible effects of ∼40 J K−1 kg−1 and up to ∼4 K upon application of ∼2 kbar and find a degradation of the first-order transition properties with pressure that limits the barocaloric effects at high pressures. Our results confirm the potential of this type of alloys for barocaloric applications, where multicaloric and composite possibilities, along with the high density and relatively high thermal conductivity, constructively add to the magnitude of the caloric effects.
A dielectric barrier discharge ion source increases thrust and efficiency of electroaerodynamic propulsion
Authors: Xu Haofeng , He Yiou , Barrett Steven R. H.
Published: June 2019

Electroaerodynamic (EAD) propulsion, which produces a thrust force by electrostatic means, has been proposed as a method of electric airplane propulsion which is solid-state and nearly silent and produces no combustion emissions. Previous work demonstrated that EAD is capable of sustaining flight of heavier-than-air airplanes. The most successful EAD propulsion devices have thus far used a direct current (DC) corona discharge to produce ions and the same DC field to accelerate them. However, these corona discharge EAD devices are subject to a performance trade-off where increasing thrust reduces efficiency (thrust-to-power ratio). This is a key barrier to practical adoption. Here, we show that by using a dielectric barrier discharge (DBD) instead of a corona discharge to produce ions, while still using a DC field to accelerate them, higher thrust and thrust-to-power can be achieved. We identify operating regimes for this thruster, optimize the electrical characteristics of the DBD ion source, and find that the thrust-to-power can reach up to 20 N/kW at a thrust of 50 mN/m and up to 10 N/kW at 150 mN/m—in both cases, approximately twice that of the equivalent corona discharge devices. With lower power draw for the same thrust, DBD enhanced EAD propulsion devices could increase the endurance of EAD airplanes and begin to enable the design of practically useful solid-state aircraft.
Two-step sub-Lorentzian structures and graph surfaces
Authors: Karmanova M. B.
Published: June 2019

We establish an area formula for graph mappings on two-step sub-Lorentzian structures with an arbitrary number of spatial and temporal directions. In a particular case, we consider an alternative approach that requires no additional smoothness of the mapping from which the graph is constructed.
A DNA toolbox for non-invasive genetic studies of sambar deer (Rusa unicolor)
Authors: Davies Chris , Wright Wendy , Wedrowicz Faye , Hogan Fiona E.
Published: June 2019

Invasive sambar deer (Rusa unicolor) are having significant detrimental impacts on natural environments in south-eastern Australia. Little, however, is known about their ecology, limiting evidence-based management strategies directed at reducing deer impacts. Genetic data, generated from DNA isolated from deer scats, can be used to fill ecological knowledge gaps. This study outlines a non-invasive genetic sampling strategy by which good-quality DNA from a single deer scat can be used to determine (1) species of origin, (2) sex and (3) a unique DNA profile. DNA from deer tissue and sambar deer scat samples were used to develop and optimise molecular methods to collect reliable genetic information. A DNA toolbox is presented that describes how to find, collect and store scat samples, isolate DNA and use molecular markers to generate informative genetic data. Generating genetic data using this approach will support studies aimed at acquiring ecological knowledge about sambar deer. Such knowledge will be critical for developing evidence-based recommendations to improve on-ground management decisions for sambar deer.
Reduced cytochrome oxidase activity and increased protein tyrosine phosphorylation of mitochondria-rich fractions of buffalo (Bubalus bubalis) spermatozoa after a cycle of freezing and thawing
Authors: Panda Arya P. , Roy Sudhir C. , Sakhare Deepak T. , Badami Sharanabasav , Divyashree Bannur C. , Gurupriya Vijayasaraswathy S. , Dhali Arindam
Published: June 2019

The motility and fertility of mammalian spermatozoa are compromised when they are cryopreserved. Sperm mitochondrial proteins play a vital role in conferring motility. However, the effects of cryopreservation on mitochondria-specific proteins remain primarily unexplored in domestic animals, including buffaloes, so the present study aimed to evaluate this issue. Mitochondria were isolated from both non-cryopreserved and cryopreserved buffalo spermatozoa by sonication followed by sucrose density gradient ultracentrifugation. The purity of the mitochondrial preparation was assessed by cytochrome oxidase assay and electron microscopy. Mitochondria separated from cryopreserved buffalo spermatozoa were associated with significantly lower (P ≤ 0.05) cytochrome oxidase activity as compared with non-cryopreserved spermatozoa. The intensities of two low-molecular-mass mitochondrial proteins (30.1 kDa and 26.1 kDa) were significantly reduced as compared with the non-cryopreserved group. In addition, in cryopreserved buffalo sperm mitochondria, the intensities of three tyrosine phosphorylated proteins (126.6, 106.7 and 26 kDa) increased significantly compared with the non-cryopreserved group. Of these, tyrosine phosphorylation of the 26-kDa mitochondrial protein of cryopreserved sperm was very intense and unique because it could not be detected in the mitochondria of non-cryopreserved sperm. Thus, the study confirmed that both cytochrome oxidase activity and the proteins of buffalo sperm mitochondria undergo significant cryogenic changes in terms of quantity and quality after a cycle of freezing and thawing and this may be one of the important causes of reduced post-thaw motility and fertility of cryopreserved buffalo spermatozoa.
Using electronic communication technologies for improving syphilis partner notification in Chile: healthcare providers' perspectives – a qualitative case study
Authors: Iturrieta-Guaita Nicole G. , Temple-Smith Meredith J. , Tomnay Jane
Published: June 2019

Background Partner notification (PN) in Australia has been studied and improved in recent decades. International researchers have highlighted the use of electronic communication technologies to assist PN (Internet partner notification or IPN). Using the Australian experience as an example, the aim of this study is to explore clinicians’ perspectives on the use of specialised websites, such as Let them know, to facilitate PN in the Chilean context. Methods: Semi-structured interviews were conducted with healthcare providers (HCPs) in 14 primary health care centres and six sexual health units located at two regional Health Services, as well as with key informants from different backgrounds. Interviews were transcribed verbatim and QSR International’s NVivo 11 PRO Software was used for cross-case thematic analysis, which followed an inductive approach. Selected quotes were translated from Spanish to English. Codes and themes were reviewed by the research team. Results: Most participants were unaware of IPN and demonstrated interest. Many agreed this could be a feasible strategy considering the high use of mobile technologies and the Internet in Chile. Participants’ primary concerns around this approach were confidentiality, privacy and efficacy, given the local cultural context. The use of a counsellor to offer professional support and guidance was identified as essential to strengthen PN in Chile. Conclusion: The use of IPN could be an alternative PN strategy for Chile. However, the involvement of local staff and further research to explore patients’ perceptions and preferences will be essential in tailoring interventions.
A
Lotus japonicus
cytoplasmic kinase connects Nod factor perception by the NFR5 LysM receptor to nodulation
Authors: Wong Jaslyn E. M. M. , Nadzieja Marcin , Madsen Lene H. , Bücherl Christoph A. , Dam Svend , Sandal Niels N. , Couto Daniel , Derbyshire Paul , Uldum-Berentsen Mette , Schroeder Sina , Schwämmle Veit , Nogueira Fábio C. S. , Asmussen Mette H. , Thirup Søren , Radutoiu Simona , Blaise Mickaël , Andersen Kasper R. , Menke Frank L. H. , Zipfel Cyril , Stougaard Jens
Published: June 2019

Significance

Legume receptors perceive Nod factor signal molecules at the plasma membrane of epidermal cells and initiate a signal transduction process that leads to the development of root nodules that house nitrogen-fixing rhizobia. Nodule organs are formed by reinitiation of cell divisions in already differentiated root cells. Previous genetic screens have identified plant genes involved in nodulation; however, the receptor-triggered relay mechanism activating the developmental program in the nucleus is still unknown. We present a proteomics approach that identified proteins that associate with the
Lotus japonicus
Nod factor receptor 5 (NFR5), among which the NFR5-interacting cytoplasmic kinase 4 (NiCK4) appears to be an important link between Nod factor perception by NFR5 and nodule organogenesis.
Cyanobacterial viruses exhibit diurnal rhythms during infection
Authors: Liu Riyue , Liu Yaxin , Chen Yue , Zhan Yuanchao , Zeng Qinglu
Published: June 2019

Significance

To adapt to the daily light–dark cycle, diurnal rhythms are used by the photosynthetic cyanobacteria
Prochlorococcus
and
Synechococcus
, which are the most abundant photosynthetic organisms on earth. Field studies revealed that cyanobacterial virus (cyanophage) populations in the oceans showed transcriptional rhythms. To explore the underlying mechanism, we used cyanophage laboratory cultures to find that some showed adsorption rhythms and all showed transcriptional rhythms. We discovered that the cyanophage transcriptional rhythm is partially caused by the photosynthetic activity of host cells, explaining transcriptional rhythms of field cyanophage populations. Our study shows that cultured viruses have diurnal infection rhythms which are critical for understanding how light–dark cycles shape the interaction of cyanophages and their hosts in the oceans.
EBV infection is associated with histone bivalent switch modifications in squamous epithelial cells
Authors: Leong Merrin Man Long , Cheung Arthur Kwok Leung , Dai Wei , Tsao Sai Wah , Tsang Chi Man , Dawson Christopher W. , Mun Yee Ko Josephine , Lung Maria Li
Published: June 2019

Significance

Epstein−Barr virus (EBV) infection is implicated in the development of certain cancers; however, the mechanisms by which EBV contributes to the pathogenesis of epithelial cell malignancies remains unclear. This study highlights the association of EBV infection with aberrant modifications in histone bivalent marks, H3K4me3 and H3K27me3, in nasopharyngeal epithelial cells. Down-regulation of the DNA damage repair pathway genes, including
MLH1
, associated with aberrant histone bivalent marks in a promoter hypermethylation-independent manner, was observed after EBV infection. This finding provides strong evidence linking EBV infection to epigenetic modifications in epithelial cells. This study also suggests that the level of MLH1 may be useful as a potential biomarker to evaluate the responsiveness of nasopharyngeal carcinoma patients to cisplatin-based therapies.