bluuebunny/crossref_metadata_2025 huggingface dataset:
INTERACTION OF PLANE WAVES WITH VERTICAL CYLINDERS
Authors: Spring Bradford H. , Monkmeyer Peter L.
Published: June 2019

This study deals with the interaction of linear, plane water waves with stationary groups of rigid, vertical, circular cylinders under conditions in which the inertial forces on the cylinders dominate over the drag forces. A direct matrix solution as well as multiple scattering as suggested by Twersky (1952) are used to obtain the velocity potential in the vicinity of the cylinders. The groups may consist of a number of cylinders having any geometric arrangement, may have Dirichlet, Neumann, or mixed boundary conditions, and need not have identical diameters. The study represents an extension of the single cylinder case presented by MacCamy and Fuchs in 1954. Basic scattering coefficients for 192 different arrangements of two cylinders are obtained with the aid of a Bessel coordinate transformation and a matrix inversion procedure. The resulting potential function is then applied to calculate force components in the direction of wave advance and orthogonal to it. For the cases considered the former departs as much as 65% from the force on a single cylinder and the mass coefficient is found to range from 1.19 to 3.38 - a not insignificant departure from the often used value of 2.0. Furthermore the orthogonal force may be as large as 67% of the single-cylinder force.
SEDIMENT TRANSPORT IN RANDOM WAVES AT CONSTANT WATER DEPTH
Authors: Wang Heiang , Liang S.S.
Published: June 2019

Sediment transport in random waves at constant water depth is analyzed by dividing the flow field into two regions-the internal region and the boundary layer region. The suspension and transport of sediment in these two regions are treated separately. The total transport is then obtained as the total of these regions through matching boundary. In the bed layer, the load concentration is assumed to be proportional to the specific weight of the sediment and to the probability that the fluctuating lifting force exceeds the weight of the sediment. The bed load is then transported by the secondary flow (which is unidirectional) in the boundary. In the internal flow region, the sediment suspension is treated as a diffusion problem with the intensity of diffusion to be proportional to the amplitude of fluid particle motion. The transport velocity is assumed to be the same as the mass transport velocity of the wave. The predominant mode of transport is found to be suspended load. The total transport in a wind-generated wave field can be expressed as a power law of wind speed. For the case tested, the power should be of the order of 4.
PERFORMANCE CHARACTERISTICS OF SUBMERGED BREAKWATERS
Authors: Dattatri J. , Raman H. , Shankar N. Jothi
Published: June 2019

Submerged breakwater is a barrier with its crest at or slightly below the still water level. In situations where complete protection from waves is not required, submerged breakwaters offer a potentially economic solution. Submerged breakwaters have been effectively used to protect harbour entrances, to reduce siltation in entrance channels, against beach erosion, and for creation of artifical fishing grounds. However quantitative information available about the hydraulic behaviour of these submerged breakwaters is rather limited. Theoretical analysis of the problem has not proved satisfactory primarily because of the difficulties in quantifying the energy losses that always accompany these wave - structure interactions. Recourse has to be taken to laboratory studies to provide the necessary information regarding the performance characteristics of submerged breakwaters. A comprehensive laboratory investigation to evaluate the performance characteristics of the submerged breakwaters of various types and shapes, permeable and impermeable was undertaken. The results of these investigations are presented in this paper.
WAVE POWER AND BEACH-STAGES: A GLOBAL MODEL
Authors: Short Andrew D.
Published: June 2019

A three-dimensional morphodynamic model of sequential beach changes Is presented. The model Is based on variations in breaker wave power generating a predictable sequence of beach conditions. The spectrum of beach conditions from fully eroded-dissipatlve to fully accreted reflective is characterised by ten beach-stages. Using the breaker wave power to beach-stage relationship the model Is applied to explain temporal, spatial and global variations In beach morphodynamlcs.
TIDAL PRISM-INLET AREA RELATIONS FOR SMALL TIDAL INLETS
Authors: Byrne R.J. , Gammisch R.A. , Thomas G.R.
Published: June 2019

Fourteen tidal inlets within the lower Chesapeake Bay were studied to examine whether significant differences existed in their hydraulic behavior relative to the larger oceanic inlets hitherto studied. Measurements included simultaneous external and internal tides, gauging of discharge through a tidal cycle, measurements of inlet geometry, and basin area. The results indicate that: a.) smaller inlets (A,- < 100 m ) depart from the relationship between inlet throat area and tidal prism developed for oceanic inlets; b.) examination of inlet width versus depth indicates the departure from ocean inlet geometry occurs at Ac values between 100 and 500 m ; c.) the maximum velocity in smaller inlets is significantly less than oceanic inlets (-0.35 vs 1.0 m/s); d.) tidal phase lags and tidal range ratio were generally equal. However, for conditions of significant tide range reduction, the low water phase lags more closely approximated the tide range ratio.
A CLOSELY RESPONDING, VERSATILE WAVE TUNNEL
Authors: Hulsbergen C.H. , Bosman J.J.
Published: June 2019

A new wave tunnel is presented as has been recently built at the Delft Hydraulics Laboratory. Several design aspects of the wave tunnel will be discussed and special attention is drawn to the required force and power diagrams.
WAVE ATTENUATION AND WAVE SET-UP ON A COASTAL REEF
Authors: Gerritsen Franciscus
Published: June 2019

In attempting to specify criteria for the design of structures on coastal reefs, it was found that no adequate method existed to derive those criteria from the deep water wave conditions. In order to fill the gap, a program of measurements and analysis was initiated at the University of Hawaii. The program consisted of prototype and laboratory measurements. Great emphasis was placed on reliable field data, which were collected on Ala Moana Reef, in Honolulu. Laboratory investigations on the behavior of waves on shallow reefs are subject to scale effects; verification from field observations is required to obtain reliable results. As a result of this study, a mathematical model was developed for the calculation of wave attenuation and wave set-up on a shallow reef, using the incident waves in the ocean as boundary conditions. This paper discusses the general behavior of waves approaching a shallow reef and presents some essential characteristics of the mathematical model. The study is limited to waves approaching the shoreline at right angles. The results of this study can be extended to breakwaters with wide, submerged berms.
INVESTIGATIONS ON ORBITAL VELOCITIES AND PRESSURES IN IRREGULAR WAVES
Authors: Daemrich K.F. , Eggert W.D. , Cordes H.
Published: June 2019

This paper deals with the results of hydraulic model investigations of orbital velocities and pressures in irregular waves. Different simulation methods in the time and frequency domain were checked or developed, and the theoretical results compared with measurements. Using simulation methods based on linear wave theory, results with good correlation are obtained, at locations near the water surface, however, a tendency towards over- or underestimation exists.
WIND TURBULENCE OVER SEAS IN TROPICAL CYCLONES
Authors: Melbourne W.H. , Blackman D.R.
Published: June 2019

A study of wind data collected from the Waglan Island anemometer (Hong Kong) during 39 tropical cyclones indicates that turbulence intensity values in excess of 20% at a reference height of 50 m are likely during extreme wind conditions in a tropical cyclone. The implied surface drag coefficient of approximately 0.01 in these extreme wind conditions is consistent with wind flow over a land surface roughness of trees and suburban housing, but is much higher (by a factor of five) than that predicted by the currently accepted formulae from the reviews of Garratt and Wu for wind flow over a fully developed sea in neutral atmospheric conditions. For wind loading design calculations in extreme wind in tropical cyclone conditions it is recommended that mean wind and turbulence intensity profiles should be calculated with a roughness length zQ = 0.20 m in the Deaves and Harris wind model.
EXPERIMENTS ON BEACH PROFILE CHANGE WITH A LARGE WAVE FLUME
Authors: Kajima Ryoichi , Shimizu Takao , Maruyama Kohki , Saito Shozo
Published: June 2019

Two-dimensional beach profile changes were investigated with a newly constructed prototype-scale wave flume. The flume is 205 m long, 3.4 m wide and 6 m deep. Sand of two grain sizes was used in the experiments. Analysis of the results was made through use of the parameter C, introduced by Sunamura and Horikawa (1974) to classify beaches as either erosional and accretionary. Beach profile changes obtained in the flume were similar to those in the prototype (field). Net sand transport rate distributions were classified into five types, two of which do not seem to have been observed in laboratory (smallscale) experiments. A simple model describing the five types was developed for evaluating two-dimensional beach profile changes.
INCIPIENT MOTION OF PARTICLES UNDER OSCILLATORY FLOW
Authors: Lenhoff L.
Published: June 2019

This paper is aimed at the establishment of a generally applicable criterion for the onset of grain motion under the influence of oscillatory flow. Data from previous studies are used in a dimensional analysis and an empirically derived relationship between the dimensionless parameters R* (shear Reynolds number) and D* (dimensionless grain parameter) is proposed as a criterion to be used in coastal engineering problems. This study forms part of a larger programme by the Sediment Dynamics Division of the National Research Institute for Oceanology in Stellenbosch, RSA, which is aimed at the reevaluation and updating of the input parameters and relationships for the predictive equations for coastal sediment transport.
NUMERICAL SIMULATION OF STORM SURGES INDUCED BY TROPICAL STORMS IMPINGING ON THE BANGLADESH COAST
Authors: Dube S.K. , Sinha P.C. , Roy G.D.
Published: June 2019

In the present paper a vertically integrated coastal zone numerical model has been described for the simulation of the surges generated by the tropical storms striking the Bangladesh coast. The model is fully nonlinear and uses a conditionally stable explicit finite- difference scheme for solving the relevant equations of motion. In this model the analysis area extends from 87°E to 93°E along the south coast of Bangladesh and there are three open-sea boundaries situated along 87°E, 93°E and 19°N. The model utilises a curvilinear boundary treatment to represent the coastline and uses a non-uniform off-shore grid spacing adjacent to the coastal boundary. This allows an increased resolution near the Bangladesh coast. Using a forcing wind-stress distribution representative of the 1970 Chittagong cyclone, we compare the model predicted surges with the observed sea-surface elevations along the Bangladesh coast. The predicted peak surge elevation above mean sea level compares well with the observed values at Chittagong port. A comparison of the results has also been made with those obtained from the corresponding model having uniform off-shore grid spacing.
THE ROLE OF SUSPENDED SEDIMENT IN SHORE-NORMAL BEACH PROFILE CHANGES
Authors: Jaffe Bruce E. , Sternberg Richard W. , Sallenger Asbury H.
Published: June 2019

Field measurements of suspended sediment-transport were made across a dissipative surf zone during a storm. A correlation between high suspended mass in the water column and periods of onshore flow caused a net onshore transport of suspended sediment even though the mean near-bottom flow was directed offshore. The observed onshore migration of a nearshore bar was predicted by gradients in the crossshore suspended-sediment transport.
THE DESIGN OF BREAKWATERS USING QUARRIED STONES
Authors: Baird W.F. , Hall K.R.
Published: June 2019

The majority of rubble mound breakwaters built in North America that use quarried stones in their armour layer contain either one or two layers of armour stone, one or two filter layers and a core of quarry run. Preparation of a design normally involves use of the Hudson equation and may be supported by physical model tests. Once the design wave conditions are defined the size of armour stones are only a function of the outer slope of the breakwater. In this paper an alternative approach to the design of quarried stone breakwaters is discussed. The basic principal involved in this concept is the use of locally available materials. It is established that the greater the thickness of the armour layer, the smaller the stones that are required to provide stable protection against wave action. Therefore, the thickness of the armour layer for a specific breakwater is determined by the gradation of the available armour stones and the incident wave climate. The final cross-section makes allowance for the practical considerations of breakwater construction. New concepts for breakwaters that have resulted from the use of this alternative design procedure are described. Construction of these breakwaters in 1983-84 has demonstrated that significant cost savings are obtained.
NEAR BOTTOM VELOCITIES IN WAVES WITH A CURRENT; ANALYTICAL AND NUMERICAL COMPUTATIONS
Authors: Van Kesteren W.G.M. , Bakker W.T.
Published: June 2019

In this paper, starting from the Prandtl hypothesis a three-dimensional numerical bottom boundary layer model has been developed, which allows to calculate bottom friction by a combination of waves and currents. The model has been compared with two-dimensional analytical computations which gave similar results. The bottom friction values found are comparable to the ones, found by Lundgren (1972), however in the most relevant cases somewhat less. Furthermore in the two-dimensional case the model has been compared with measurements of Bakker and Van Doom (1978). With respect to the oscillatory motion, still some minor deviations occur between theory and measurements, due to deficiencies of the Prandtl theory.
SEDIMENT TRANSPORT DUE TO BREAKING WAVES
Authors: Shibayama Tomoya , Higuchi Akihiko , Horikawa Kiyoshi
Published: June 2019

In the surf zone, the agitation of the bed materials by breaking waves is strong and the suspended sand concentration in the vicinity of the wave plunging point is extremely high. Sand movement in this region was observed and sand concentration was measured in a wave flume. The sand movement in the region was divided into the following two categories: 1) sand suspension due to the large vortex which is created by wave plunging, and 2) sand deposition under turbulent flow. The condition for exciting this suspension process was considered and the result was well explained by the two parameters which are the deep water wave steepness and the bottom slope. Then a numerical model of the sediment suspension process was formulated and the process was well simulated by the model.
BEACH CHANGES BY STORM WAVES
Authors: Takeda Ichiro , Sunamura Tsuguo
Published: June 2019

Monitoring of beach profiles was carried out during one-year period at two sites located 3 km apart along a Pacific beach, Japan. These two sites are composed of beach sand with different grain size: 0.76 mm and 0.26 mm. It was found that the shoreline did not move even in storm wave events at the site with 0.7 6-mm sand, where the "seesaw mode" profile change took place in the subaerial portion of the beach. It was also found that the shoreline was not always retreated by storm waves at the 0.26-mm sand site, where the "parallel mode" profile change dominated, at the time of presence of bars working as a submerged breakwater to protect the beach from erosion.
COASTAL ARMORING: EFFECTS, PRINCIPLES AND MITIGATION
Authors: Dean R.G.
Published: June 2019

An attempt is made to conduct a rational assessment of the potential adverse effects of coastal armoring on adjacent shorelines and to propose methodology for mitigation, where appropriate. Specific attention is directed toward claims that armoring causes: profile steepening, increased longshore sediment transport, intensified local scour, transport of sand to substantial offshore distances, etc. The assessment presented here is based on a combination of sound principles and the availability or lack, of laboratory and field data to either support or refute the claims. Although it is found that data relating to coastal armoring effects are sparse, conclusions can be drawn. There seems to be no factual data to support the contentions that armoring causes profile steepening, increased longshore transport, transport of sand to a substantial distance offshore, or significantly delayed profile recovery following a severe erosion event. Armoring does have the potential to cause intensified local scour both in front of and at the ends of an armored segment. Reasons for these effects, based on knowledge of response of a natural profile, are presented. Additionally, armoring which projects into the active surf zone can act as a partial barrier to the net longshore sediment transport, thereby causing downdrift erosion. Methodology is presented for quantifying the appropriate mitigation for a particular armoring situation. The proposed mitigation is the annual placement of sand in the vicinity of the armoring to offset its potential adverse effects. The two potential adverse effects addressed in the methodology include the reduction of sediment supplied to the system as a result of the armoring and the blockage of longshore sediment transport by a protruding armoring installation.
A PARABOLIC REFRACTION-DIFFRACTION EQUATION IN THE RAT-FRONT COORDINATE SYSTEM
Authors: Isobe Masahiko
Published: June 2019

The parabolic equation method has been extensively used for combined refraction and diffraction problems of water waves. However, a parabolic equation is valid only when the direction of wave propagation nearly coincides with that of a coordinate; therefore, the validity ranges of the parabolic equations developed so far are restricted. In order to achieve a wide range of validity, a parabolic equation is derived in this paper by employing a curvilinear coordinate system which has a pattern similar to that of wave rays and fronts. A computer program which is applicable to an arbitrary arrangement of coastal structures is then developed. Results of numerical calculations are compared with available analytical solutions and laboratory data. It is proved that the present parabolic equation has a high accuracy for a wide range of incident wave direction and structure arrangement.
BEACH FILL AT TWO COASTS OF DIFFERENT CONFIGURATIONS
Authors: Deguchi Ichiro , Sawaragi Toru
Published: June 2019

Movements of borrow sand replenished at two coasts of different configurations are investigated by analyzing the topographic data which were surveyed periodically after the beach fill placements. One is a long straight beach and borrow sand was placed behind a submerged breakwater. Another is a pocket beach which has an arcshoreline with a groyne at one end and a headland at another. It is found that the amount of borrow sand moved in the longshore direction surpasses the amount of borrow sand transported in the cross-shore direction regardless of the shape of the coast. A clear correlation is also found between displacements of shoreline and changes of sectional areas. These results imply that the deformation of the artificially nourished beach and the dissipation rate of borrow sand can be predicted by the so-called one-line theory.
HYDRODYNAMIC CHARACTERISTICS OF WAVE-POWER-EXTRACTING CAISSON BREAKWATER
Authors: Takahashi Shigeo
Published: June 2019

The wave power extracting caisson breakwater can convert the wave energy into usable energy. The function and the stability of the caisson as a breakwater are investigated experimentally. It is found that wave reflection and wave transmission of the breakwater are relatively small and that the stability of the breakwater caisson against storm waves is high. The design method of the caisson is proposed considering the impact air pressure in the air chamber.
TRANSFORMATION OF SHALLOW WATER WAVE SPECTRA
Authors: Bendykowska Genowefa , Werner Gosta
Published: June 2019

Investigations are presented, on some effects of nonlinearity in the motion of shallow water wave spectra. The waves were generated, mechanically in a laboratory wave flume with fixed bottom. Essential differences with the linear dispersion relation are found, showing vanishing dispersivity of higher frequency spectral components in strongly nonlinear spectra. The mean frequency increases with decreasing water depth. The relation of the peak frequency to the mean frequency varied in the experiments from 0.9 to 0.5, for deep to shallow water wave spectra respectively.
LABORATORY EXPERIMENTS ON THE INFLUENCE OF WIND ON NEARSHORE WAVE BREAKING
Authors: Douglass Scott L. , Weggel J. Richard
Published: June 2019

The influence of wind on nearshore breaking waves was investigated in a laboratory wave tank. Breaker location, geometry, and type depended upon the wind acting on the wave as it broke. Onshore winds tended to cause waves to break earlier, in deeper water, and to spill: offshore winds tended to cause waves to break later, in shallower water, and to plunge. A change in wind direction from offshore to onshore increased the surf zone width by up to 100%. Wind's effect was greatest for waves which were near the transition between breaker types in the absence of wind. For onshore winds, it was observed that microscale breaking can initiate spilling breaking by providing a perturbation on the crest of the underlying wave as it shoals.
COASTAL ENGINEERING 2008
Authors: Smith Jane McKee
Published: June 2019

*** Available Only Through World Scientific ***

http://www.worldscibooks.com/engineering/7342.html

This proceedings contains papers presented at the 31st International Conference on Coastal Engineering, which has held in Hamburg, Germany (31 August – 5 September 2008). The proceeding is divided into five parts: Waves; Long Waves, Nearshore Currents, and Swash; Sediment Transport and Morphology; Coastal Management, Environment, and Risk; and Coastal Structures. The papers cover a broad range of topics including theory, numerical and physical modeling, field measurements, case studies, design, and management. Coastal Engineering 2008 provides coastal engineers, scientists, and planners, with state-of-the-art information on coastal engineering and coastal processes.
Centrifugal Separation
Authors: Sabbagh Reza , Nobes David
Published: June 2019

Separation by density difference, compaction, and drainage is presented, along with formulas developed for bottle centrifuges, solid wall centrifuges, disk centrifuges, and hydrocyclones. The Σ‐concept development and several practical variants are discussed. Liquid–liquid separation interface location formulas are reviewed. An updated performance chart for selection and design is provided. Models for centrifuge energy consumption based on Σ‐concept are discussed. Centrifuge components, including a breakdown of power and energy losses with applicable information for centrifuges, are represented. Centrifuge materials of construction and their corrosion, erosion, and strength characteristics are reviewed. Stresses generated owing to rotation and process materials, abrasion resistance, and noise generated by centrifuges are discussed. The various types of sedimentation and filtration equipment are reviewed. Examples of use, rates, and performance of bottle; disk; decanter; preparation; zonal; tubular; perforated basket; inverting filter; conical; and continuous single‐ and multistage pusher centrifuges are reviewed. For a brief discussion of gas centrifuges and their use in uranium enrichment, please see the previous editions.
Gold Nanoparticles
Authors: Sajanlal Panikkanvalappil Ravindranathan , Khatun Esma , Pradeep Thalappil
Published: June 2019

Gold nanoparticles (GNPs) have been the most extensively studied colloidal systems in the area of nanoscience and nanotechnology owing to their fascinating physical and chemical properties. Nanoscience and nanotechnology are often inseparable from advances in GNPs. Diversity in the modes of preparation, unique properties, unusual stability in comparison to related materials make GNPs ideal for a vast array of applications in chemistry, biology, engineering, and medicine. This article gives an overview of the fascinating area of GNPs. The rich history of GNPs is briefly reviewed in the beginning of the article followed by a concise description of various pioneering synthetic strategies and their properties. An overview of novel anisotropic gold nanostructures is described in the subsequent section. Because of the importance of assembled nanostructures in tuning the collective properties of nanomaterials, assemblies of diverse GNPs are briefly described. Furthermore, a few interesting aspects of supported GNPs have also been outlined. Toward the end of the article, we have highlighted important applications of GNPs and have given a special mention of a new category of ultra‐small materials of gold known as atomically precise clusters. The article ends with the new directions of GNPs and outlines the prospects of future applications.
2‐ and N6‐functionalized adenosine‐5′‐diphosphate analogs for the inhibition of mortalin
Authors: Moseng Mitchell A. , Nix Jay C. , Page Richard C.
Published: June 2019

Our early efforts to find a covalent inhibitor of mortalin, a member of the 70 kDheat shock protein (Hsp70) family, led us to solve the structure of the mortalin nucleotide‐binding domain (NBD) in complex with N6‐propargyladenosine‐5′‐diphosphate. The acquired structure emphasizes the ability of the nucleotide‐binding pocket to accommodate modifiedADPcompounds. A library ofADPanalogs modified at either the 2‐ or N6‐positions of adenosine was screened against the mortalin‐NBD. Competitive inhibition and binding assays of the analogs demonstrate that modifications at the 2‐ or N6‐positions have potential to bind and inhibit mortalin uniquely compared to other Hsp70 homologs, and that modifications at the 2‐position confer the greatest selectivity in binding and inhibition of the mortalin‐NBD.
Structural and biochemical analysis of a phosin fromStreptomyces chartreusisreveals a combined polyphosphate‐ and metal‐binding fold
Authors: Werten Sebastiaan , Rustmeier Nils Hinnerk , Gemmer Maximilian , Virolle Marie‐Joëlle , Hinrichs Winfried
Published: June 2019

X‐ray crystallographic analysis of a phosin (PptA) fromSteptomyces chartreusisreveals a metal‐associated, lozenge‐shaped fold featuring a 5–10 Å wide, positively charged tunnel that traverses the protein core. Two distinct metal‐binding sites were identified in which the predominant metal ion was Cu2+. In solution, PptA forms stable homodimers that bind with nanomolar affinity to polyphosphate, a stress‐related biopolymer acting as a phosphate and energy reserve in conditions of nutrient depletion. A single protein dimer interacts with 14–15 consecutive phosphate moieties within the polymer. Our observations suggest that PptA plays a role in polyphosphate metabolism, mobilisation or sensing, possibly by acting in concert with polyphosphate kinase (Ppk). Like Ppk, phosins may influence antibiotic synthesis by streptomycetes.
Radiological tissue equivalence of deformable silicone‐based chemical radiation dosimeters (FlexyDos3D)
Authors: Du Yi , Wang Ruoxi , Wang Meijiao , Yue Haizhen , Zhang Yibao , Wu Hao , Wang Weihu
Published: June 2019

FlexyDos3D, a silicone‐based chemical radiation dosimeter, has great potential to serve as a three‐dimensional (3D) deformable dosimetric tool to verify complex dose distributions delivered by modern radiotherapy techniques. To facilitate its clinical application, its radiological tissue needs to be clarified. In this study we investigated its tissue‐equivalence in comparison with water and Solid Water (RMI457). We found that its effective and mean atomic numbers were 40% and 20% higher and the total interaction probabilities for kV x‐ray photons were larger than those of water respectively. To assess the influence of its over‐response to kV photons, its HU value was measured by kV computed tomography (CT) and was found higher than all the soft‐tissue substitutes. When applied for dose calculation without correction, this effect led to an 8% overestimation in electron density via HU‐value mapping and 0.65% underestimation in target dose. Furthermore, depth dose curves (PDDs) and off‐axis ratios (profiles) at various beam conditions as well as the dose distribution of a full‐arc VMAT plan in FlexyDos3D and reference materials were simulated by Monte Carlo, where the results showed great agreement. As indicated, FlexyDos3D exhibits excellent radiological water‐equivalence for clinical MV x‐ray dosimetry, while its nonwater‐equivalent effect for low energy x‐ray dosimetry requires necessary correction. The key findings of this study provide pertinent reference for further FlexyDos3D characterization research.
Surface Texturing in Machine Elements − A Critical Discussion for Rolling and Sliding Contacts
Authors: Rosenkranz Andreas , Grützmacher Philipp G. , Gachot Carsten , Costa Henara L.
Published: June 2019

Surface texturing has gained great attention in the tribological community since precisely defined surface features can help to reduce friction and/or wear irrespective of the acting lubrication regime. The ability to positively influence tribological performance under different lubrication conditions makes surface texturing particularly interesting for machine elements since they may experience different conditions over the lifetime or sometimes even over one cycle/stroke. However, despite the great effort by both researchers and industry to introduce surface texturing in machine elements, many questions remain unclear regarding the optimal design of surface textures, as well as the positive and negative effects on the component's performance. The aim of this review article is to critically summarize the state of the art of surface texturing applied to machine elements, with a special emphasis on piston rings, seals, roller bearings, and gears. After a brief introduction, the first section focuses on surface texturing in sliding components (piston rings and seals), whereas the second section deals with surface texturing in rolling components (roller bearings and gears). Based upon the main evidence from the literature, the final section provides more general design guidelines for surface texturing in machine elements.
Microstructural Evolution, Room‐ and High‐Temperature Mechanical Properties of Friction Welded Joints of a New Wrought Ni–Fe Based Superalloy
Authors: Xu Yaxin , Li Wenya , Lu Jintao , Wang Guilong , Dang Yingying , Yang Zheng , Gu Yuefeng , Yang Zhiyuan , Sui Yupeng
Published: June 2019

A new wrought Ni–Fe‐based superalloy, designed for the advanced ultra‐supercritical power plant (A‐USC), is successfully joined by rotary friction welding (RFW), followed by post‐weld heat treatment (PWTH). The microstructural evolution and mechanical properties of the joints are systematically investigated by optical microscopy, scanning electron microscopy, microhardness, and tensile tests at both room temperature and 750 °C. The results show that dynamic recrystallization and dissolution of strengthening phases have occurred in the weld during FW, in which γ′ dissolves to a larger extent than M23C6 or MC carbides. The microstructure of the as‐welded joint including the grain size, shape, and the distribution of precipitates gradually changes from the weldline to the parent alloy. Consequently, the as‐welded joints exhibit relatively poor mechanical properties due to the dissolution of γ′ which becomes even worse at 750 °C because of the grain‐boundary sliding. After PWHT, the as‐welded microstructure can be homogenized by grain growth and the re‐precipitation of strengthening phases, which is responsible for the remarkable improvement in tensile strength at both room and high temperature after PWHT. This study gives new insights into the high‐quality welding of the newly developed Ni–Fe‐based superalloy.
A Review on High Entropy Alloys Coatings: Fabrication Processes and Property Assessment
Authors: Li Junchen , Huang Yongxian , Meng Xiangchen , Xie Yuming
Published: June 2019

Surface coatings can enhance the mechanical and functional properties of substrates and keep good balance between specific mechanical properties and sufficient surface performance of the components. Coatings composed of high entropy alloys (HEAs) and HEA‐based materials, including metallic, ceramics, and composites have attracted the global attention and developed rapidly over the last decade, owing to their outstanding properties. Here, the authors provide a critical review of the state‐of‐the‐art for HEA‐based coatings, aiming to address the related conceptions, designing principles, microstructural, and mechanical evolutions during fabrication and post‐treatments process. The surface properties which are not limited to anti‐corrosion, anti‐radiation, and anti‐diffusion and their underlying mechanisms are analyzed. The development tendency and future applications are classified and discussed, including the basic researches about HEAs, the regulations of fabrication techniques and the exploring of functional properties of HEA‐based coatings. Due to their superior mechanical and functional potentials as well as abundant element‐constitutions of designing, surface coatings composed of HEA‐based materials are considered to have promising applications in engineering and industrial manufacturing.
Enhanced Dynamic Adhesion in Nematic Liquid Crystal Elastomers
Authors: Ohzono Takuya , Saed Mohand O. , Terentjev Eugene M.
Published: June 2019

Smart adhesives that undergo reversible detachment in response to external stimuli enable a wide range of applications in household products, medical devices, or manufacturing. Here, a new model system for the design of smart soft adhesives that dynamically respond to their environment is presented. By exploiting the effect of dynamic soft elasticity in nematic liquid crystal elastomers (LCE), the temperature‐dependent control of adhesion to a solid glass surface is demonstrated. The adhesion strength of LCE is more than double in the nematic phase, in comparison to the isotropic phase, further increasing at higher detachment rates. The static work of adhesion, related to the interfacial energy of adhesive contact, is shown to change very little within the explored temperature range. Accordingly, the observed enhanced adhesion in the nematic phase is primarily attributable to the increased internal energy dissipation during the detachment process. This adhesion effect is correlated with the inherent bulk dynamic‐mechanical response in the nematic LCE. The reported enhanced dynamic adhesion can lead to the development of a new class of stimuli‐responsive adhesives.
Tools for Measuring Clinical Ultrasound Competency: Recommendations From the Ultrasound Competency Work Group
Authors: Damewood Sara C. , Leo Megan , Bailitz John , Gottlieb Michael , Liu Rachel , Hoffmann Beatrice , Gaspari Romolo J.
Published: June 2019

Competency in clinical ultrasound is essential to ensuring safe patient care. Competency in clinical ultrasound includes identifying when to perform a clinical ultrasound, performing the technical skills required for ultrasound image acquisition, accurately interpreting ultrasound images, and incorporating sonographic findings into clinical practice. In this concept paper, we discuss the advantages and limitations of existing tools to measure ultrasound competency. We propose strategies and future directions for assessing competency in clinical ultrasound.
Electrolyte effects on recirculating dense bubbly flow: An experimental study using X‐ray imaging
Authors: Mandalahalli Manas M. , Wagner Evert C. , Portela Luis M. , Mudde Robert F.
Published: June 2019

In this work, the effect of an electrolyte (up to 2 M of NaCl dissolved in water) on a homogeneous dense bubbly flow, in an airlift bubble column, is studied using nonintrusive techniques. X‐ray and high‐speed imaging are used to investigate the bubble size distribution, the local and the global gas‐fraction profiles. The major effect of the electrolyte is the bubble size distribution at the fine‐pore sparger, which is a consequence of the bubble coalescence inhibition promoted by the electrolyte. The bubble plume widening, the increase in overall gas fraction, and the onset of bubble recirculation in the column can all be explained by the bubble size reduction at the fine‐pore spargers. As a result of the bubble size reduction, the overall role of the electrolyte is in a reduction of the driving force for the liquid recirculation. Furthermore, an accumulation of the small bubbles causes a layer of foam at the free surface, which is dynamic in nature and induces additional bubble recirculation.
The Implementation of Mindfulness‐Based, Trauma‐Informed Parent Education in an Underserved Latino Community: The Emergence of a Community Workforce
Authors: Burns Barbara M. , Merritt Jennifer , Chyu Laura , Gil Roberto
Published: June 2019

Highlights

Community‐led parent education to strengthen resilience in low‐resource community

Community‐led partnership was driven by the commitment and cultural expertise of community workforce.

Parent education as a new training model to engage and mobilize community resilience
From Mexico to Michigan and back: An international collaboration investigating primate behavior, ecology, and evolution from multiple perspectives
Authors: Cortés‐Ortiz Liliana , Espinosa Domingo Canales , Dias Pedro D. , Bergman Thore , Kitchen Dawn M.
Published: June 2019

Evolutionary research benefits form the integration of laboratory and field components to determine factors and processes that affect the evolutionary trajectories of species. Our shared interest in understanding hybridization with genetic admixture as a process that may impact social, behavioral, and ecological features of primates, brought us together in a collaborative project aimed at addressing how vocal variation in two species of howler monkeys in Mexico affects and is affected by hybridization. To achieve this goal, we joined our academic expertise in studying primate genetics, ecology, and behavior under different natural and experimental conditions. We took advantage of decades of experience studying and handing wild howler monkeys for translocation projects to safely sample and study wild populations for this project. Here, we describe the history of our collaboration highlighting how our different perspectives, academic realities, and individual strengths built the foundation for our successful collaboration. We also share our perspectives on how this collaboration opened up new academic venues, broadened our individual perspectives on the integration of different research approaches to address a complex topic, and allowed us to recognize the strength of international collaboration.
Spatial and episodic memory tasks promote temporal lobe interictal spikes
Authors: Vivekananda Umesh , Bush Daniel , Bisby James A. , Diehl Beate , Jha Ashwani , Nachev Parashkev , Rodionov Roman , Burgess Neil , Walker Matthew C.
Published: June 2019

Reflex epilepsies have been demonstrated to exploit specific networks that subserve normal physiological function. It is unclear whether more common forms of epilepsy share this particular feature. By measuring interictal spikes in patients with a range of epilepsies, we show that 2 tasks known to specifically engage the hippocampus and temporal neocortex promoted increased interictal spiking within these regions, whereas a nonhippocampal dependent task did not. This indicates that interictal spike frequency may reflect the processing demands being placed on specific functional–anatomical networks in epilepsy. ANN NEUROL 2019;86:304–309
Presymptomatic spinal cord pathology in c9orf72 mutation carriers: A longitudinal neuroimaging study
Authors: Querin Giorgia , Bede Peter , El Mendili Mohamed Mounir , Li Menghan , Pélégrini‐Issac Mélanie , Rinaldi Daisy , Catala Martin , Saracino Dario , Salachas François , Camuzat Agnes , Marchand‐Pauvert Véronique , Cohen‐Adad Julien , Colliot Olivier , Le Ber Isabelle , Pradat Pierre‐François ,   for the Predict to Prevent Frontotemporal Lobar Degeneration and Amyotrophic Lateral Sclerosis Study Group
Published: June 2019

Objective

C9orf72 hexanucleotide repeats expansions account for almost half of familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) cases. Recent imaging studies in asymptomatic C9orf72 carriers have demonstrated cerebral white (WM) and gray matter (GM) degeneration before the age of 40 years. The objective of this study was to characterize cervical spinal cord (SC) changes in asymptomatic C9orf72 hexanucleotide carriers.

Methods

Seventy‐two asymptomatic individuals were enrolled in a prospective study of first‐degree relatives of ALS and FTD patients carrying the c9orf72 hexanucleotide expansion. Forty of them carried the pathogenic mutation (C9+). Each subject underwent quantitative cervical cord imaging. Structural GM and WM metrics and diffusivity parameters were evaluated at baseline and 18 months later. Data were analyzed in C9+ and C9− subgroups, and C9+ subjects were further stratified by age.

Results

At baseline, significant WM atrophy was detected at each cervical vertebral level in C9+ subjects older than 40 years without associated changes in GM and diffusion tensor imaging parameters. At 18‐month follow‐up, WM atrophy was accompanied by significant corticospinal tract (CST) fractional anisotropy (FA) reductions. Intriguingly, asymptomatic C9+ subjects older than 40 years with family history of ALS (as opposed to FTD) also exhibited significant CST FA reduction at baseline.

Interpretation

Cervical SC imaging detects WM atrophy exclusively in C9+ subjects older than 40 years, and progressive CST FA reductions can be identified on 18‐month follow‐up. Cervical SC magnetic resonance imaging readily captures presymptomatic pathological changes and disease propagation in c9orf72‐associated conditions. ANN NEUROL 2019;86:158–167
A functional substitution in the L‐aromatic amino acid decarboxylase enzyme worsens somatic symptoms via a serotonergic pathway
Authors: Khoury Samar , Piltonen Marjo H. , Ton Anh‐Tien , Cole Tiffany , Samoshkin Alexander , Smith Shad B. , Belfer Inna , Slade Gary D. , Fillingim Roger B. , Greenspan Joel D. , Ohrbach Richard , Maixner William , Neely G. Gregory , Serohijos Adrian W. R. , Diatchenko Luda
Published: June 2019

Objective

Heightened somatic symptoms are reported by a wide range of patients with chronic pain and have been associated with emotional distress and physical dysfunction. Despite their clinical significance, molecular mechanisms leading to their manifestation are not understood.

Methods

We used an association study design based on a curated list of 3,295 single nucleotide polymorphisms mapped to 358 genes to test somatic symptoms reporting using the Pennebaker Inventory of Limbic Languidness questionnaire from a case–control cohort of orofacial pain (n = 1,607). A replication meta‐analysis of 3 independent cohorts (n = 3,189) was followed by functional validation, including in silico molecular dynamics, in vitro enzyme assays, and measures of serotonin (5‐HT) plasma concentration.

Results

An association with the T allele of rs11575542 coding for an arginine to glutamine substitution in the L‐aromatic amino acid decarboxylase (AADC) enzyme was replicated in a meta‐analysis of 3 independent cohorts. In a combined meta‐analysis of all cohorts, this association reached p = 6.43 × 10−8. In silico studies demonstrated that this substitution dramatically reduces the conformational dynamics of AADC, potentially lowering its binding capacity to a cofactor. in vitro enzymatic assays showed that this substitution reduces the maximum kinetic velocity of AADC, hence lowering 5‐HT levels. Finally, plasma samples from 90 subjects showed correlation between low 5‐HT levels and heightened somatic symptoms.

Interpretation

Using functional genomics approaches, we identified a polymorphism in the AADC enzyme that contributes to somatic symptoms through reduced levels of 5‐HT. Our findings suggest a molecular mechanism underlying the pathophysiology of somatic symptoms and opens up new treatment options targeting the serotonergic system. ANN NEUROL 2019;86:168–180
Autism and developmental disability caused by KCNQ3 gain‐of‐function variants
Authors: Sands Tristan T. , Miceli Francesco , Lesca Gaetan , Beck Anita E. , Sadleir Lynette G. , Arrington Daniel K. , Schönewolf‐Greulich Bitten , Moutton Sébastien , Lauritano Anna , Nappi Piera , Soldovieri Maria Virginia , Scheffer Ingrid E. , Mefford Heather C. , Stong Nicholas , Heinzen Erin L. , Goldstein David B. , Perez Ana Grijalvo , Kossoff Eric H. , Stocco Amber , Sullivan Jennifer A. , Shashi Vandana , Gerard Benedicte , Francannet Christine , Bisgaard Anne‐Marie , Tümer Zeynep , Willems Marjolaine , Rivier François , Vitobello Antonio , Thakkar Kavita , Rajan Deepa S. , Barkovich A. James , Weckhuysen Sarah , Cooper Edward C. , Taglialatela Maurizio , Cilio M. Roberta
Published: June 2019

Objective

Recent reports have described single individuals with neurodevelopmental disability (NDD) harboring heterozygous KCNQ3 de novo variants (DNVs). We sought to assess whether pathogenic variants in KCNQ3 cause NDD and to elucidate the associated phenotype and molecular mechanisms.

Methods

Patients with NDD and KCNQ3 DNVs were identified through an international collaboration. Phenotypes were characterized by clinical assessment, review of charts, electroencephalographic (EEG) recordings, and parental interview. Functional consequences of variants were analyzed in vitro by patch‐clamp recording.

Results

Eleven patients were assessed. They had recurrent heterozygous DNVs in KCNQ3 affecting residues R230 (R230C, R230H, R230S) and R227 (R227Q). All patients exhibited global developmental delay within the first 2 years of life. Most (8/11, 73%) were nonverbal or had a few words only. All patients had autistic features, and autism spectrum disorder (ASD) was diagnosed in 5 of 11 (45%). EEGs performed before 10 years of age revealed frequent sleep‐activated multifocal epileptiform discharges in 8 of 11 (73%). For 6 of 9 (67%) recorded between 1.5 and 6 years of age, spikes became near‐continuous during sleep. Interestingly, most patients (9/11, 82%) did not have seizures, and no patient had seizures in the neonatal period. Voltage‐clamp recordings of the mutant KCNQ3 channels revealed gain‐of‐function (GoF) effects.

Interpretation

Specific GoF variants in KCNQ3 cause NDD, ASD, and abundant sleep‐activated spikes. This new phenotype contrasts both with self‐limited neonatal epilepsy due to KCNQ3 partial loss of function, and with the neonatal or infantile onset epileptic encephalopathies due to KCNQ2 GoF. ANN NEUROL 2019;86:181–192
Utilizing Carbonyl Coordination of Native Amides for Palladium‐Catalyzed C(sp3)−H Olefination
Authors: Park Hojoon , Li Yang , Yu Jin‐Quan
Published: June 2019

PdII‐catalyzed C(sp3)−H olefination of weakly coordinating native amides is reported. Three major drawbacks of previous C(sp3)−H olefination protocols, 1) in situ cyclization of products, 2) incompatibility with α‐H‐containing substrates, and 3) installation of exogenous directing groups, are addressed by harnessing the carbonyl coordination ability of amides to direct C(sp3)−H activation. The method enables direct C(sp3)−H functionalization of a wide range of native amide substrates, including secondary, tertiary, and cyclic amides, for the first time. The utility of this process is demonstrated by diverse transformations of the olefination products.