bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of wear reduction measures for wheelsets and rails operated in high mountain conditions
Authors: Voznenko Sergei , Falendysh Anatoliy , Sumtsov Andrey , Kletska Olha , Blatnicky Miroslav
Published: November 2018

There are about 20 major factors influencing wear of railway system of a wheel, but the most critical include service and lubricant of rails. On the basis of locomotive depot Rodakovo the analysis of regularity of wear of a surface of wheels of the locomotive during the long period of time has been made and the method of correction of wheels has been offered and calculations which have shown that during operation of wheel couples there can be several corrections of a profile of a wheel before full grinding that leads to increase in life cycle of a wheel have been carried out. Also the approximate method for assessment of efficiency of introduction of methods of maintenance and repair of a wheel which includes the cost of life cycle of a wheel of the locomotive which will be developed further has been offered, estimating at the same time several methods, comparing their efficiency and choosing the most preferable options in the set parameters.
Computerized method for estimation of ultimate load of piles
Authors: Younis Basheer , Thamer Khudhair , Kazimahomedov Firas
Published: November 2018

A new method was established to estimate the ultimate load, which is utilized in the assessment of pile test. In the present study twenty five reports of failure test piles (28.5 x 28.5 cm in dimensions, 12 m in depth and the working load was 40 ton) of Um-Alqura Mosque project were studied in according to their loading and settlement. The (mean ± SD) of the pile settlement for each load of all piles studied were determined, and the results obtained were utilized to generate the equation that correlates between the load and settlement using (4th degree polynomial fit graph). The equation obtained was applied to estimate the ultimate load for the maximum settlement (10% of the pile diameter). The estimated ultimate load (130 ton) in the present study was compared with the ultimate load (132 ton), which was determined previously using (Fellenius and Decourt presentation, 2001). The deviation between the ultimate load of the previous and the present method was (1.5%), but the present method depends on two working load, so it saves time and efforts and suitable to implement in the assessment of the test pile.
Bearing capacity of RC beams reinforced with high strength rebars and steel plate
Authors: Bobalo Taras , Blikharskyy Yaroslav , Vashkevich Rostyslav , Volynets Myhailo
Published: November 2018

Nowadays, reducing the material content of not only buildings and structures in general, but also individual constructions is a topical task that can be realized through the use of high-strength concrete and reinforcement, as well as with the use of external reinforcement. The concentrated location of sheet reinforcement on the external the most tense facets of steel and concrete structures increases the operating height of the cross-section, makes it possible to more effectively use the strength properties of steel in comparison with conventional reinforced concrete, and with the same bearing capacity to economize on expenses. Composite and monolithic reinforced concrete structures with external reinforcement are used in various construction sectors around the world. This contributed to the expansion of the use of reinforced concrete for special buildings of power-engineering and hydrotechnical construction. The technical nd econom efficiency, as well as the possibility of using external rebar as formwork for monolithic concrete construction, have been proved. Therefore, there is a need for the study of structures with combined reinforcement, in which high rigidity of steel and concrete structures is combined with an effective use of high-strength reinforcing bars (rebar) without prior tension
Bearing capacity calculation of reinforced concrete corbels under the shear action
Authors: Dovzhenko Oksana , Pohribnyi Volodymyr , Pents Volodymyr , Mariukha Dmytro
Published: November 2018

The necessity of creating a general methodology for concrete and reinforced concrete elements strength calculation under the shear is established. Three failure cases of reinforced concrete corbels under the shear are considered. The solutions of problems of corbels strength with failure along the whole section, close to the normal, in the compressed zone under an inclined crack and within the compressed inclined strip are given. A variational method in the plasticity theory, the virtual velocities principle and the characteristic lines method are used for concrete and reinforced concrete elements calculations. In the ultimate state, concrete is considered as a rigid-plastic body. The shear is realized in case when the plastic deformation is localized in the compressed zone. The calculating ultimate load results for different failure cases are given. Such a design scheme is implemented, in which the console strength is minimal. This corresponds to the minimum of power of plastic deformation in concrete compressed zone. Reinforced concrete corbels calculation engineering methods are offered. The elements obtaining effective constructive decisions direction based on the plasticity theory use is determined.
Features of modeling of energy profile of construction
Authors: Gaponova Lyudmyla , Grebenchuk Serhii , Psurtseva Nina , Kalmykov Oleg , Demyanenko Ivan
Published: November 2018

Presentation and realization of the task of rationalization of structural parameters of reinforced concrete shells is presented. As a criterion for this task an energy principle is adopted, according to which it is assumed that from the whole set of possible values of the desired parameters of the system with a constant volume of material, the number of external and internal connections, the potential energy of deformation (DER) after the reconstruction will reach the lower limit on a rational combination of values of geometric parameters. The energy principle is taken as a criteria on for this task, according to which it is believed that out of numerous possible values of the searched parameters of the system with the constant amount of material, number of external and internal connections, the strain potential energy (SPE) after the reconstruction will reach the lower limit on the rational connection of the geometrical parameters describing the system. The determined interconnection of the rational parameters of the constructive anisotropic shell between SPE of the system of internal and external rational parameters: with ribs step value of about l ≈ 1000 mm SPE reaches the lower limit.
The search for sustainable parameters for steel-reinforced concrete section of a bridge superstructure
Authors: Krul Yuriy , Kaplin Roman
Published: November 2018

The article contains the description of an efficient lightweight steel-reinforced concrete bridge superstructure, which includes metal blocks with a box-like section and reinforced concrete efficient roadway slab. Metal blocks are made of sheet perforated elements manufactured according to the no-waste technology. The blocks are interconnected as a single space bridge superstructure frame by means of high strength bolts. The reinforced concrete slab of the roadway is an efficient hollow slab. It includes upper and lower housing, inner ribs placed with a particular pitch, and all its remained part is filled with polystyrene foam extractable fillers along its height. At this, a rib height is equal to the full slab height. The metal and reinforced concrete parts are linked by means of a special system of shearing connections. The article describes an iteration algorithm of the construction enhancement, in course of which the geometrical parameters, such as bridge superstructure section full height, reinforced concrete slab thickness and a construction metal part height were defined. Theoretical models being the ground for the strain-stress state (SSS) of the sections studied analysis were developed.
Probable reliability prediction of the dam constructed with ground materials of the Nam Chien hydraulic power system in Vietnam using the Monte Carlo method
Authors: Mozgovuy Andrii , Butnik Svitlana
Published: November 2018

The current method of probabilistic safety assesses dams with ground material by the criterion of water overflow through the dam crest. Due to the stochastic nature of the material properties, loads and impacts method involves the use of the Monte Carlo method (statistical tests). The algorithm was tested on the example of the ground material dams of Nam Chien hydropower in the Vietnam.
Investigation of the regularities of temperature regime of fire in cable tunnels depending on its parameters
Authors: Nuianzin Oleksandr , Kryshtal Mykola , Nesterenko Artem , Kryshtal Dmytro , Samchenko Taras
Published: November 2018

Simulation, as a method of scientific research, makes it possible, without performing costly and labor-intensive field experiments on models, to carry out all necessary experiments to determine the temperature modes of fire in cable tunnels. The purpose of the research of this work was to determine the temperature regime of fire in a cable tunnel depending on its shape, size and fire load. Mathematical models of cable tunnels were created in one of the CFD software systems. Cable products are constantly evolving and improving. For tests on the fire resistance of building structures of cable tunnels, a standard temperature mode of fire is used which may not correspond to fire mode in a real cable tunnel. The computational experiments were carried out and the temperature regimes of fires in tunnels with different parameters were determined. The obtained results showed the parameters of cable tunnels, which influence the temperature regime of fire in tunnels most. In this paper the use of computational experiments for the study of heat and mass transfer processes in fires in cable tunnels was examined further. CFD Fire Dynamics Simulator 6.2 was used.
Calculation of the crack resistance of reinforced concrete elements with allowance for the levels of normal crack formation
Authors: Romashko Vasyl , Romashko Olena
Published: November 2018

The separate experimental investigations results and the major drawbacks of existing methods of calculating the reinforced concrete elements crack resistance are considered in detail, taking into account the process of multilevel formation and crack opening. Based on the basic provisions of the deformation and strength model of concrete and reinforced concrete resistance, an engineering method for calculating the formation and disclosure of normal cracks in the reinforced concrete elements and structures at the operational stages of their deformation is proposed. It is implemented on the system of generally accepted static, geometric and physical relations of a deformed solid mechanics. The simplicity of the proposed calculation method is due to the use of the nonlinear function of the average stresses of the reinforcement bond with concrete on the sections of the reinforced concrete element between adjacent cracks. The main advantages of the developed calculation method in comparison with others are outlined.
Disperse reinforcing of alkaline aluminosilicate binders for protection materials of structures
Authors: Krivenko Pavel , Kyrychok Volodymyr
Published: November 2018

The review of the literature and the analysis of the problem of durability and reduction of cracking of binders and materials for the protection of building structures have been carried out, an effective method of improving their cracking resistance during the entire lifetime has been proposed. The influence of reinforcement of the matrix of alkaline aluminosilicate binders on their technological and physical-mechanical properties was investigated. According to the study of influence reinforcing components on the properties of binders, it should be noted that the highest the conditional coefficient of crack resistance is characterized by the contents containing in its composition as a reinforcing component of the basalt scales. The microstructure of the connecting substance and the contact zone “compound substance - the reinforcing component” has been analyzed, the type and the optimum amount of the reinforcing component have been established to provide the technological and operational properties of the materials for the protection of building structures.
Modelling the loss of time caused by traffic incidents on motorways
Authors: Birr Krystian , Strzebrakowska Barbara
Published: November 2018

For each road incident important factors like location, capacity reduction, traffic management, duration of road incidents and amount of traffic should be defined. All performer operations and effects of incidents affect the capacity of the road, average speed, time loss, vehicle queues and traffic jams. In the article road incidents were divided into planned and unexpected. Statistical analysis prepared using the database of traffic events which occurred on highways and expressways in Pomeranian Voivodeship is presented considering location of incidents on each road, frequency and duration of incidents and duration of rescue operation. Furthermore, the cases used to calibrate the model are characterised. Subsequently, the method of estimation of time loss resulting from incidents is presented. Within the methodology, mathematical and simulation models are distinguished. The tools for dynamic traffic modelling are also presented. In the last part of the article, the method of calculation value of time loss is presented.
Assessing vehicle restraint systems on horizontal curves
Authors: Budzyński Marcin , Bruski Dawid
Published: November 2018

Horizontal curves, an element of road infrastructure, have a statistically high number of accidents. Considering that horizontal curves in the last ten years have had app. 10% of all road accidents representing app. 14% of all fatalities on Polish roads, the issue is serious and requires more research and proper road safety treatments. Data for 2007 - 2016 show that in the case of accidents on horizontal curves app. 45% of the fatalities happened as a result of crashing into roadside obstacles such as signs and first of all trees. This shows that horizontal curves require road safety equipment, and specifically, safety barriers. Key to this is using the right equipment and the right parameters. To achieve that, full-scale crash tests should be conducted to be followed by numerical tests. The article will present a synthesis of the available research conducted in Poland and abroad. An assessment will be made of four crash tests of TB32 with barriers that have a steel and cable guardrail. They are the outcome of the RID 3A “Road safety equipment” project called RoSE. Building on these tests, numerical test results will be presented.
Analysing the impact of traffic incidents on express road traffic flow using FREEVAL
Authors: Ciszewska-Kulwińska Eliza , Romanowska Aleksandra , Kustra Wojciech
Published: November 2018

Traffic incidents occurring on motorways or express roads cause disruptions and deteriorate traffic conditions. The impact will differ depending on the type of incident, its duration and space blocked on the roadway and can be measured with e.g. average speed reduction, extension of travel time, time lost or overall costs of traffic disruptions. The aim of the paper is to analyse this impact, based on data from the Tri-City Ring Road (Poland). The analyses were conducted on a macroscopic level, with the use of a simulation software FREEVAL. The analysed road section was divided into homogeneous basic, merge and diverge segments. Particular traffic disturbances were introduced into individual segments, in order to represent a traffic accident or short-term road works leading to a blocked shoulder, closure of 1 lane or 2 lanes for the duration of 15 to 60 minutes. The total of 150 scenarios were analysed. The results of the analyses helped to assess how travel time and vehicle speed change depending on the location, type and duration of the traffic incident. It was found, for example, that in the case of right shoulder blockage, travel time will not change significantly (up to 3%) while the closing of 1 of 2 or 2 of 3 lanes will cause significant travel time extension (by over 500%).
The impact of exploitation and environmental factors on the degradation of steel road safety equipment
Authors: Kobus Joanna , Kwiatkowski Lech , Lutze Rafał
Published: November 2018

The work is aimed at determining the corrosivity of atmosphere in the vicinity of roads, taking into account the characteristics of local emission sources, including traffic intensity of vehicles along with climatic and exploitation factors. Determination of the corrosivity of atmosphere was carried out according to the procedures described in PN EN ISO standards. Samples for testing were made of low carbon steel DC05, zinc and hot dip galvanized steel. Samples were assembled at 19 sites in the close vicinity of roads and highways near the measurement points of vehicle traffic intensity. The mass loss of exposed samples was the basis for determination the atmosphere corrosivity at each of 19 test sites. Regarding steel, the corrosivity category of C4 was observed at 8/19 sites. Corrosion losses outside roads are 2-4 times lower and ranged within the categories of C2 and C3. Zinc corrosion losses classified to category C4 occurred at 2/19 stations. In the remaining ones they corresponded to category C3. In areas outside of roads, zinc corrosion losses are about 20-100% lower (C2). The first attempts to model the dependence of operating and environmental parameters on zinc and zinc coating corrosion losses indicate significant correlation between zinc and zinc coating corrosion losses as a function.
Laboratory tests of how selective factors impact the durability and functionality of road safety steel devices
Authors: Rudnik Dariusz , Klasik Adam , Grobelny Marcin , Rostek Ewa
Published: November 2018

Road safety devices, such as guides and wire rope barriers have a direct impact on road safety. These devices are mounted close to the road therefore they are exposed to mechanical damage and corrosive factors, which causes them to degrade subsequently leading to adverse changes of the useful properties. The objective of research was to determine the influence of exploitation factors (corrosion, mechanical damage) on the functionality changes of these selected steel road safety elements. Samples for testing mechanical properties were taken from guides and wire rope material in delivery condition and after exposure to a corrosive environment. In order to simulate mechanical damage, samples were cut or holes were made or they were gravelled. In the case of wires taken from ropes, tensile tests of wires subjected to pre-cycles of fatigue load corresponding to cycles of changes in rope stress in operating conditions were also performed.
Photometric and geometrical characteristics of advertising media installed in the road environment
Authors: Tomczuk Piotr , Chrzanowicz Marcin
Published: November 2018

Advertising media are located in such a way that they are visible to road users and the visual information reaches the driver regardless of whether the media is located in or outside the lane. Road managers have limited possibilities to influence technical parameters of media placed outside the roadway. However, the light emitted from the advertising medium reaching the driver may be subject to limitations. Subject literature indicates the necessity of using emission parameters in relation to technical parameters of media. The current requirements in Poland specify the maximum luminance values of the advertising media. However, a number of other relevant vehicle emission parameters which may degrade the driver's visual perception of the driver's road environment shall not be taken into account. The need to introduce guidelines for the installation of roadside advertising requires the presentation and discussion of specific technical parameters concerning light emission from the advertising medium. In the article have been discussed of emission parameters of advertising media and examples of measurements of individual lighting parameters, which are possible to be registered in field conditions.
Application of RAMS analysis in road transport
Authors: Graboń-Chałupczak Marzena , Sitarz Mareks
Published: November 2018

Despite the many advantages, each type of transport, there are many people for the health and life of people. This means that some of the challenges that are not productive have higher energy levels. Substitution of the instrument's characteristics. Management of the fleet of tourist company arders enabling the company to improve and client's operational affairs on the elements of reliability, service compliance, readiness and security (RAMS). The RAMS method used in railway transport has found application in monitoring the maintenance of railway vehicles in maintenance management system and the IRIS Standard. In the article, the authors present the method of assessing the technical maintenance of road vehicles based on the elements used in the RAMS analysis.
Influence of selected ITS services on the driver’s behaviour - results of simulation test carried out on top-of-the-range driving simulators
Authors: Kamiński Tomasz , Pędzierska Małgorzata , Filipek Przemysław
Published: November 2018

The publication is a summary of the test results, using top-of-the-range driving simulators in RID 4D project. Experiment methodology and example of research results were presented in the article entitled: "The use of simulator studies to assess the impact of ITS services on the behaviour of the road users". The project was implemented as part of the Road Innovation Development (RID) program organized and financed by the National Centre for Research and Development and General Directorate of National Roads and Motorways (contract No. DZP/RID-I-41/7/NCBR/2016). The results of the research were used to assess the impact of ITS services on the driver’s behaviour and to calibrate the simulation software Visum/Saturn/Vissim. The result of a series of experiments is a set of data including speed, speed changes, the length of the road section on which the driver maintained constant speed and additional information on the driver’s behaviour. Information for the drivers was presented on boards and signs of variable content. The vehicle speed was analyzed along a distance of 200 m, 30 m, and then at the location spot of the variable content sign/board and 200 m after the sign. The data was also recorded in the case of the traditional speed-limiting sign.
Brief-ANT as a tool for measuring the influence of roadside advertisements content on the drivers’ attentional processes
Authors: Olejniczak-Serowiec Anna , Maliszewski Norbert , Harasimczuk Justyna
Published: November 2018

The question of roadside advertisement’s influence on road safety is complex and multi-faceted. The list of advertisements characteristics which may play significant role for road safety includes: the size, colours, shape, luminance, contrast, localization, and many more. One of the aspects is advertisement’s content. Advertising industry uses emotional and cognitive mechanisms which are likely to engage the addressees’ attention and therefore make the brand/product more salient for their minds. As far as such a strategy might be effective for advertisers, it may be dangerous for road safety, when used in roadside advertisement. Cognitive, especially attentional, resources play key role in vehicle driving, which requires constant maintenance of situational awareness. Attention distraction, both visual and cognitive, is a proven safety-decreasing factor in vehicle driving. A method for measuring the influence of different advertisement content on attentional resources management - a short, version of the ANT, Brief-ANT, was developed. The results of a nationwide study conducted, revealed that reaction time in Brief-ANT differed significantly depending on the type of content used as the fixation cue, which leads us to a conclusion that Brief-ANT might be a good measure of the content’s influence on attentional resources management.
Analysis of the advancements in real-life performance of highly automated vehicles' with regard to the road traffic safety
Authors: Matysiak Arkadiusz , Razin Paula
Published: November 2018

The article presents the analysis of the performance of the vehicles equipped with automated driving systems (ADS) which were tested in real-life road conditions from 2015 to 2017 in the state of California. It aims at the effort to assess the impact on the road safety the continuous technological advancements in driving automation might have, based on of the first large-scale, real-life test deployments. Vehicle manufacturers and other stakeholders testing the highly automated vehicles in California are obliged to issue yearly reports which provide an insight on the test scale as well as the technology maturity. The so-called 'disengagement reports' highlight the range and number of control takeovers between the ADS and driver, which are made either based on driver's decision or information provided by the vehicle itself. The analysis of these reports allowed to investigate the development made in automated driving technology throughout the years of tests, as well as the direct or indirect influence of the external factors (e.g. various weather conditions) on the ADS performance. The results show that there is still a significant gap in reliability and safety between human drivers and highly automated vehicles which has been yet steadily decreasing due to technology advancements made while driving in the specific infrastructure and traffic conditions of California.
Effect of vehicle motion stability after impact/crash on traffic safety
Authors: Mieloszyk Eligiusz , Milewska Anita , Grulkowski Sławomir
Published: November 2018

The article presents the application of general stability theory to the study of road traffic stability immediately after an impact (crash, collision). It turns out that when modelling a collision, vehicles can be treated as colliding masses and dynamical systems can be assigned to this phenomenon.
Applicability of the Functional Resonance Analysis Method in urban transport
Authors: Smoczyński Piotr , Kadziński Adam , Gill Adrian , Anna Kobaszyńska-Twardowska
Published: November 2018

Functional resonance is a novel approach of explaining how adverse events happen in complex socio-technical systems. It stresses the fact that such systems in most of the cases function without any negative consequences due to their internal adaptiveness, called resilience. Therefore, this approach is particularly suitable to domains with relatively high level of safety, where there is not much data on incidents and accidents form the past. It can also be used for describing other analyses domains in order to better understand their resilience mechanisms. The literature review performed with help of Scopus database shows clearly that the topic of functional resonance is getting more and more attention in the scientific world. The research aiming to develop the FRAM or using it as a tool for various kinds of safety analyses is being published in the best journals from a variety of disciplines, especially the Engineering. Transportation system was the domain of the research in four investigated papers; three times the aviation transport and once – maritime transport. There was no publication in the urban transportation, although the FRAM is applicable also in this domain.
A hybridised CSAGA method for damage detection in structural elements
Authors: Sahu Sasmita , Kumar Priyadarshi Biplab , Parhi Dayal R.
Published: November 2018

In recent years, significant developments have been noticed in nondestructive techniques for damage detection in cracked structures. Some of the proposed methods can be used to find out the existence of the crack; other methods locate and simultaneously find out the damage severity. In the current investigation, a novel hybridised method is proposed for damage detection in structural elements. The proposed method can be used to investigate both location and nature of damage in structures within a reasonable time limit. The problem in the current analysis requires a set of dynamic parameters that depend on the dynamics of the cracked structure due to the presence of the crack. In the present study, the first three natural frequencies of a structure are considered as the inputs to find out the damage location. A finite element method is used to generate the first three natural frequencies of a cracked cantilever beam with multiple cracks. A method hybridizing the nature-inspired artificial intelligence techniques has been implemented for crack detection. Here, clonal selection algorithm and genetic algorithm have been integrated to design the framework of the hybrid technique. The changes in the natural frequencies are given as inputs to the hybrid technique and the output from the technique is the locations of damage.
New species of Paracolpenteron n. gen. and Ancyrocephalus (Monogenea, Dactylogyridae) inhabiting the urinary bladder and gills of the Maya needlefish Strongylura hubbsi (Beloniformes, Belonidae) from Chiapas, Mexico
Authors: Mendoza-Franco Edgar F. , Caspeta-Mandujano Juan M. , Ramírez-Martínez Carlos
Published: November 2018

Parasitological examination of the maya needlefish Strongylura hubbsi Collette (Belonidae) from the Rio Lacantún basin in the Montes Azules Biosphere Reserve, Chiapas, Mexico showed that specimens were parasitized by two monogenean species in two different sites: Paracolpenteron hubbsii n. gen., n. sp in the urinary bladder and Ancyrocephalus chiapanensis n. sp in the gill lamellae. Paracolpenteron hubbsii differs from other dactylogyrid species without a haptoral anchor/bar complex infecting the urinary systems, gills and nasal cavities by the general morphology of hooks, a dextral vaginal opening, a tubular male copulatory organ comprising a base from which a coiled shaft arises in counterclockwise direction, and an unarticulated Y-shaped accessory piece. Ancyrocephalus chiapanensis n. sp. resembles Ancyrocephalus cornutus William & Rogers, 1972 from the gills of Strongylura marina from Florida from which it differs in possessing a twisted tube of the male copulatory organ (curved in A. cornutus), ventral bar with cavities on the ends (cavities absent in A. cornutus) and by the size of the ventral (length 31–34 μm vs. 24–27 μm in A. cornutus) and dorsal (length 25–28 μm vs. 18–22 μm in A. cornutus) anchors. These new monogeneans are described herein and their biogeography is briefly discussed based on the previous phylogenetic hypotheses concerning the host family.
A transferable artificial neural network model for atomic forces in nanoparticles
Authors: Jindal Shweta , Bulusu Satya S.
Published: November 2018

We have designed a new method to fit the energy and atomic forces using a single artificial neural network (SANN) for any number of chemical species present in a molecular system. The traditional approach for fitting the potential energy surface for a multicomponent system using artificial neural network (ANN) is to consider n number of networks for n number of chemical species in the system. This shoots the computational cost and makes it difficult to apply to a system containing more number of species. We present a new strategy of using a SANN to compute energy and forces of a chemical system. Since atomic forces are significant for geometry optimizations and molecular dynamics simulations for any chemical system, their accurate prediction is of utmost importance. So, to predict the atomic forces, we have modified the traditional way of fitting forces from underlying energy expression. We have applied our strategy to study geometry optimizations and dynamics in gold-silver nanoalloys and thiol protected gold nanoclusters. Also, force fitting has made it possible to train smaller sized systems and extrapolate the parameters to make accurate predictions for larger systems. This proposed strategy has definitely made the mapping and fitting of atomic forces easier and can be applied to a wide variety of molecular systems.
Interfacial structure of SrZrxTi1−xO3 films on Ge
Authors: Chen Tongjie , Ahmadi-Majlan Kamyar , Lim Zheng Hui , Zhang Zhan , Ngai Joseph H. , Kemper Alexander F. , Kumah Divine P.
Published: November 2018

The interfacial structure of SrZrxTi1−xO3 films grown on semiconducting Ge substrates is investigated by synchrotron X-ray diffraction and first-principles density functional theory. By systematically tuning the Zr content x, the effects of bonding at the interface and epitaxial strain on the physical structure of the film can be distinguished. The interfacial perovskite layers are found to be polarized as a result of cation-anion ionic displacements perpendicular to the perovskite/semiconductor interface. We find a correlation between the observed buckling and valence band offsets at the SrZrxTi1−xO3/Ge interface. The trends in the theoretical valence band offsets as a function of Zr content for the polar structures are in agreement with reported X-ray photoelectron spectroscopy measurements. These results have important implications for the integration of functional oxide materials with established semiconductor based technologies.
Ignition in ternary Ru/Al-based reactive multilayers—Effects of chemistry and stacking sequence
Authors: Pauly C. , Woll K. , Gallino I. , Stüber M. , Leiste H. , Busch R. , Mücklich F.
Published: November 2018

While self-propagating reactions in metallic multilayers have been known since the early 1990s, the vast majority of research has been conducted on binary systems comprising either elemental or alloyed layers. The properties of reaction and ignition in these samples are, for a given composition, mainly determined by the bilayer thickness as main design parameter. Here, we present how the stacking sequence is established as an additional design parameter when going from binary to ternary layered systems. The basis for this study is reactive Ru/Al multilayers which are extended to ternary samples by introducing a third element (Ni, Pt, or Hf) as a third, individual component. It is shown that exothermic solid state reactions at the layer interfaces and grain boundaries control the ignition temperature. Furthermore, the stacking sequence determines the specific volume density of phase boundaries and, thus, the magnitude of contribution of these reactions to the process of ignition. While the addition of hafnium is found to have little to no effect on ignition, nickel and platinum lower the ignition temperatures by up to 150 °C (Ni) and 230 °C (Pt), respectively. This can be attributed to the exothermic formation of Ni2Al9, amorphous a-(Al,Pt), and Pt2Al3 which are formed at temperatures significantly lower than that of RuAl6 which is the driving reaction for ignition in binary Ru/Al multilayers.
Cooperative epidemics spreading under resource control
Authors: Li Jiayang , Yang Chun , Fu Chuanji , Gao Yachun , Yang Hongchun
Published: November 2018

The input and allocation of public resources are of crucial importance to suppressing the outbreak of infectious diseases. However, in the research on multi-disease dynamics, the impact of resources has never been taken into account. Here, we propose a two-epidemic spreading model with resource control, in which the amount of resources is introduced into the recovery rates of diseases and the allocation of resources between two diseases is regulated by a parameter. Using the dynamical message passing method, we obtain resource thresholds of the two diseases and validate them on ER networks and scale-free networks. By comparing the results on scale-free networks with different power-law exponents, we find that the heterogeneity of the network promotes the spreading of both diseases. Especially, we find optimal allocation coefficients at different resource levels. And, we get a counterintuitive conclusion that when the available resources are limited, it is a better strategy to preferentially suppress the disease with lower infection rate. In addition, we investigate the effect of interaction strength and find that great interaction strength between diseases makes two diseases with different infectivity tend to be homogeneous.
Diagnosing and mitigating laser preheat induced mix in MagLIF
Authors: Harvey-Thompson A. J. , Weis M. R. , Harding E. C. , Geissel M. , Ampleford D. J. , Chandler G. A. , Fein J. R. , Glinsky M. E. , Gomez M. R. , Hahn K. D. , Hansen S. B. , Jennings C. A. , Knapp P. F. , Paguio R. R. , Perea L. , Peterson K. J. , Porter J. L. , Rambo P. K. , Robertson G. K. , Rochau G. A. , Ruiz D. E. , Schwarz J. , Shores J. E. , Sinars D. B. , Slutz S. A. , Smith G. E. , Smith I. C. , Speas C. S. , Whittemore K.
Published: November 2018

A series of Magnetized Liner Inertial Fusion (MagLIF) experiments have been conducted in order to investigate the mix introduced from various target surfaces during the laser preheat stage. The material mixing was measured spectroscopically for a variety of preheat protocols by employing mid-atomic number surface coatings applied to different regions of the MagLIF target. The data show that the material from the top cushion region of the target can be mixed into the fuel during preheat. For some preheat protocols, our experiments show that the laser-entrance-hole (LEH) foil used to contain the fuel can be transported into the fuel a significant fraction of the stagnation length and degrade the target performance. Preheat protocols using pulse shapes of a few-ns duration result in the observable LEH foil mix both with and without phase-plate beam smoothing. In order to reduce this material mixing, a new capability was developed to allow for a low energy (∼20 J) laser pre-pulse to be delivered early in time (−20 ns) before the main laser pulse (∼1.5 kJ). In experiments, this preheat protocol showed no indications of the LEH foil mix. The experimental results are broadly in agreement with pre-shot two-dimensional HYDRA simulations that helped motivate the development of the early pre-pulse capability.
Ultrawide strain-tuning of light emission from InGaAs nanomembranes
Authors: Wang Xiaowei , Cui Xiaorui , Bhat Abhishek , Savage Donald E. , Reno John L. , Lagally Max G. , Paiella Roberto
Published: November 2018

Single-crystal semiconductor nanomembranes provide unique opportunities for basic studies and device applications of strain engineering by virtue of mechanical properties analogous to those of flexible polymeric materials. Here, we investigate the radiative properties of nanomembranes based on InGaAs (one of the standard active materials for infrared diode lasers) under external mechanical stress. Photoluminescence measurements show that, by varying the applied stress, the InGaAs bandgap energy can be red-shifted by over 250 nm, leading to efficient strain-tunable light emission across the same spectral range. These mechanically stressed nanomembranes could therefore form the basis for actively tunable semiconductor lasers featuring ultrawide tunability of the output wavelength.
A trilayer stacked tunneling medium enhances spin injection into graphene
Authors: DeJarnette Drew
Published: November 2018

The injection of electron spins into graphene is improved by 50 percent over previous works using a trilayer hexagonal boron nitride buffer as a tunneling layer between the graphene and cobalt alloy contacts.
Functional near-infrared spectroscopy: A promising noninvasive brain imaging tool under natural conditions
Authors: Zhang Zhengzheng
Published: November 2018

Perspectives on the challenges and promises of functional near-infrared spectroscopy as a noninvasive and portable neuroimaging tool for brain studies.
Cu-based perovskite thin-film hybrids reveal unusual magnetic properties
Authors: Wolverton Mark
Published: November 2018

Organic-inorganic perovskitelike hybrids open new possibilities for magnetic thin films.
Partitioning mortality into growth-dependent and growth-independent hazards across 203 tropical tree species
Authors: Camac James S. , Condit Richard , FitzJohn Richard G. , McCalman Lachlan , Steinberg Daniel , Westoby Mark , Wright S. Joseph , Falster Daniel S.
Published: November 2018

Significance

We present a model that partitions rates of tropical tree mortality into growth-dependent and growth-independent hazards. This creates the opportunity to examine the relative contributions of within-species and across-species variation on tropical tree mortality rates, but also how species traits affect each hazard. We parameterize this model using >400,000 observed survival records collected over a 15-y period at Barro Colorado Island, Panama from more than 180,000 individuals across 203 species. We show that marginal carbon budgets are a major contributor to tree death on Barro Colorado Island. Moreover, we found that while species’ light demand, maximum diameter at breast height (dbh), and wood density affected tree mortality in different ways, they explained only a small fraction of the total variability observed among species.
Gut health in poultry and considerations of additives as alternatives to antibiotics.
Authors: Broom L. J. , Kogut M. H.
Published: November 2018

Gut health' is currently a hot topic in animal production but lacks precise definition or definitive assessment. Antibiotics have been used for many years to manage gut health issues but are under pressure in many parts of the world to help protect their long-term effectiveness. The intestine is composed of numerous components, including a microbiome, nutrients and host factors (e.g. cells, secretions, mediators, etc.) that are continually interacting. The gut microbiome governs the development and functionality of the immune system and strongly influences 'gut health'. Features of the innate gut immune system are largely present and functionally mature at hatch and may represent a particular focus for exogenous interventions. Inflammation is a key innate response and, although often viewed only as a negative response, evidence indicates an enhanced or less regulated acute inflammatory response capability is beneficial. Unresolved, sterile or metabolic inflammation, resulting from innate immune system stimulation by non-infectious cellular components and metabolites, are, however, generally recognized as undesirable and are a focus for intervention. Antibiotic growth promoters were effective at preventing and/or controlling intestinal disorders and although most evidence suggests benefits from microbiome modification there is still debate over the precise mode of action. The clear protective effects of the gut microbiome and influences on immunity make for potential interventions that have largely focused on the application of various microbiome (e.g. probiotics) and/or immune (e.g. cytokines) modulators. A better understanding of key microbiome-immune interactions, and thus how these can be appropriately modulated, is essential for significant progress in promoting gut and animal health.
TREK-1 channels regulate pressure sensitivity and calcium signaling in trabecular meshwork cells
Authors: Yarishkin Oleg , Phuong Tam T.T. , Bretz Colin A. , Olsen Kenneth W. , Baumann Jackson M. , Lakk Monika , Crandall Alan , Heurteaux Catherine , Hartnett Mary E. , Križaj David
Published: November 2018

Mechanotransduction by the trabecular meshwork (TM) is an essential component of intraocular pressure regulation in the vertebrate eye. This process is compromised in glaucoma but is poorly understood. In this study, we identify transient receptor potential vanilloid isoform 4 (TRPV4) and TWIK-related potassium channel-1 (TREK-1) as key molecular determinants of TM membrane potential, pressure sensitivity, calcium homeostasis, and transcellular permeability. We show that resting membrane potential in human TM cells is unaffected by “classical” inhibitors of voltage-activated, calcium-activated, and inwardly rectifying potassium channels but is depolarized by blockers of tandem-pore K+ channels. Using gene profiling, we reveal the presence of TREK-1, TASK-1, TWIK-2, and THIK transcripts in TM cells. Pressure stimuli, arachidonic acid, and TREK-1 activators hyperpolarize these cells, effects that are antagonized by quinine, amlodipine, spadin, and short-hairpin RNA–mediated knockdown of TREK-1 but not TASK-1. Activation and inhibition of TREK-1 modulates [Ca2+]TM and lowers the impedance of cell monolayers. Together, these results suggest that tensile homeostasis in the TM may be regulated by balanced, pressure-dependent activation of TRPV4 and TREK-1 mechanotransducers.
The Relative Impact of Community and Hospital Antibiotic Use on the Selection of Extended-spectrum Beta-lactamase–producing Escherichia coli
Authors: MacFadden Derek R , Fisman David N , Hanage William P , Lipsitch Marc
Published: November 2018

Antibiotic stewardship programs have traditionally focused on reducing hospital antibiotic use. However, reducing community antibiotic prescribing could have substantial impacts in both hospital and community settings. We developed a deterministic model of transmission of extended-spectrum beta-lactamase–producing Escherichia coli in both the community and hospitals. We fit the model to existing, national-level antibiotic use and resistance prevalence data from Sweden. Across a range of conditions, a given relative change in antibiotic use in the community had a greater impact on resistance prevalence in both the community and hospitals than an equivalent relative change in hospital use. However, on a per prescription basis, changes in antibiotic use in hospitals had the greatest impact. The magnitude of changes in prevalence were modest, even with large changes in antimicrobial use. These data support the expansion of stewardship programs/interventions beyond the walls of hospitals, but also suggest that such efforts would benefit hospitals themselves.
The Impact of Antibiotic Stewardship Program Resources on Infection Prevention Programs
Authors: Bleasdale Susan C , Barnden Marsha , Barnes Sue
Published: November 2018

Doernberg and colleagues describe the role and resourcing of the infectious disease (ID) physician for an effective hospital-based antibiotic stewardship program (ASP). There are similar resource requirements for the ID physician leader in an effective infection prevention (IP) program. This ID physician partnership is supported by professional organizations and predates the imperative of ID physician leadership in ASP. There are regulatory requirements for established IP programs, but they do not specify leadership structure to the same degree as ASP regulations. The Centers for Medicare and Medicaid and The Joint Commission have specified the inclusion of an ID-trained physician leader in ASP, and this has led to the development of curriculum to train more ASP physicians. More robust advocacy may ensure a similar regulatory mandate supporting the participation of ID-trained physicians in IP programs. This may encourage the development of a curriculum to meet the workforce.