bluuebunny/crossref_metadata_2025_split huggingface dataset:
Additively Manufactured High-Performance Elastocaloric Materials with Long Fatigue Life
Authors: Hou Huilong , Simsek Emrah , Ma Tao , Johnson Nathan S. , Qian Suxin , Cissé Cheikh , Stasak Drew , Al Hasan Naila , Zhou Lin , Hwang Yunho , Radermacher Reinhard , Levitas Valery I. , Kramer Matthew J. , Asle Zaeem Mohsen , Stebner Aaron , Ott Ryan T. , Cui Jun , Takeuchi Ichiro 
Published: May 2022

Abstract
Elastocaloric cooling, which exploits superelastic transitions of shape memory alloys to pump heat, has recently emerged as a frontrunner in alternative cooling technologies. Despite its intrinsic high efficiency, elastocaloric materials exhibit hysteresis associated with input work, a common attribute of caloric cooling materials. In this study, the authors created a Ni-Ti-based elastocaloric material by additive manufacturing nanocomposite materials using a laser directed-energy- deposition system. The material exhibited exceptional stability and unusual operational efficiency derived from the unique and intricate nanocomposite structures made by additive manufacturing. This demonstration shows the potential for using additive manufacturing to optimize caloric cooling by providing a highly desirable topology flexibility into materials components that serve as both refrigerants and heat exchangers.
Extending the Fatigue Life of NiTiHf High Temperature Shape Memory Alloys through Partial Thermal Cycling
Authors: Demblon A. , Mabe J.H. , Karaman I. 
Published: May 2022

Abstract
NiTiHf high temperature shape memory alloys (HTSMAs) are being used in an ever-growing array of applications, specifically in the aerospace and automotive industries. One of the difficulties facing further implementation is ensuring the actuation fatigue lifetime is sufficiently long as to prevent the HTSMA components from being a limiting factor to the mean time between failures of a system. Another potential problem for widespread use is the deterioration of actuation stroke during lifetime, which can be problematic when attempting to have a high-fidelity repeatable design. One way of solving these issues is to optimize the microstructure through careful control of composition, processing, and heat treatments. Current research shows composition of large-scale productions is incredibly difficult to control, and small deviations in composition (~0.1 at.% Ni) can result in changes in transformation temperature by 50?C or more. Four NiTiHf compositions were investigated. The initial goal to simply extend the actuation fatigue lifetime and provide a stable actuation response morphed into determining material factors that influence the actuation response of partially cycled samples.
Spiral Laminal Flow Technology in a Self-Expanding Nitinol Stent: Investigation on the Manufacturing Process
Authors: Bernini M. , Lucchetti A. , Dunlop C. , Hellmuth R. , Ronan W. , Vaughan T. J. 
Published: May 2022

Abstract
Self-expanding Nitinol stents are the preferred treatment for atherosclerotic diseases in femoral arteries. However, adverse clinical outcomes are recorded and mostly attributed to altered flow dynamics caused by the device, which can lead to in-stent restenosis in 15% to 32% of stented segments within 9 to 15 months post-intervention. Spiral laminar flow (SLF) technology consists of a helical ridge on the inner surface of the device, which recovers the natural helical blood flow downstream and reduces flow disturbance and turbulence caused by stenting, thus preventing disease progression. This study presents the manufacturing process developed to obtain the SLF technology on self-expanding Nitinol devices, either laser-cut or braided, and addresses the optimal manufacturing parameters to ensure mechanical performance (radial strength, crush load resistance) and physical characteristics (phase transition temperature, surface finishing) appropriate for endovascular applications.
Simulation of Pseudoelastic NiTi Shape Memory Alloys under Compressive Loading to Assess the Potential use in Vibration Damping in the Tool Interface
Authors: Zwinscher Yannic , Hoffmann Fabian , Horn Simon , Krieg Romina , Theiß Ralf , Dültgen Peter , Klumpen Niclas , Brecher Christian , Neus Stephan 
Published: May 2022

Abstract
Passive vibration isolation is a key element to achieve precise results in milling processes and to increase tool durability. Damping of vibrations near to the cutting edge is considered highly effective as well as hard to implement because of the limited damping properties of conventional materials in the available space. The use of damping elements made of NiTi shape memory alloys (SMA) represents an innovative approach. Their use is based on the ability to convert mechanical energy into thermal energy through the pseudoelastic effect, whereby the pronounced conversion hysteresis of the material provides information about the usable damping potential. Studies on the properties of pseudoelastic SMA under compressive loading are only sporadically available in comparison to tensile loading. In this paper, the stress-compression curves and the hysteresis energy of tests results are compared with the results of finite element simulations. The simulation results based on the material model used so far is a good basis for the further development of damping elements.
Epitaxial NiTi Thin Films: A 3D Puzzle
Authors: Lünser K. , Schwabe S. , Nielsch K. , Fähler S. 
Published: May 2022

Abstract
NiTi films are widely used in micro applications due to their shape memory and superelasticity properties. When customizing the material for a specific miniature device, it is vital to understand the underlying martensitic microstructure, how it forms, and how it affects the shape memory effect. Up to now, most research on the martensitic microstructure in NiTi concentrates on NiTi bulk, but results derived from bulk materials are not always applicable for films as well. Even though polycrystalline NiTi films are widely available, these films contain grain boundaries, which hamper or even inhibit a scale bridging analysis of the martensitic microstructure. Therefore, the martensitic microstructure in NiTi films and its formation remains mostly unexplored. To improve NiTi for applications in miniature devices, it is thus helpful to study films without grain boundaries as model systems. In this study, the authors analyze single crystalline NiTi films grown by DC magnetron sputter deposition. These epitaxial films grow without large angle grain boundaries and make it possible to analyze the martensitic microstructure over several length scales. The work analyzed the martensitic microstructure and its nucleation with microscopy and X-ray methods and compared these measurements with orientation relationships calculated with the phenomenological theory of martensite. The results are the starting point to understand the formation of a hierarchical martensitic microstructure of NiTi in three dimensions.
An Elastocaloric Air Cooler with Low-Force Bending Actuation
Authors: Li Xueshi , Sun Qingping 
Published: May 2022

Abstract
Elastocaloric cooling has emerged as a promising alternative to traditional vapor-compression refrigeration. Attempts to develop elastocaloric devices have been made in recent years, with substantial achievements in realizing large temperature span and high coefficient of performance (COP). Moreover, miniaturization of these devices will be highly beneficial in commercializing the elastocaloric cooling. In this work, the authors report a bending approach to induce the phase transformation of NiTi sheet with advantages of low force actuation and high temperature change, while performances of elastocaloric air cooler based on the bending mode are demonstrated and analyzed.
Features of Deformation of Thin Superelastic TiNi Wire
Authors: Marchenko E.S. , Baigonakova G.A. , Gunther S.V. , Mamazakirov O. 
Published: May 2022

Abstract
TiNi-based wire is widely used in the manufacture of surgical implants and designs due to its biocompatibility and ability to undergo viscoelastic deformation with tissues, withstanding millions of deformation cycles without destruction. TiNi is a self-passivating material, as it forms a complex surface oxide layer that protects the material from corrosion and is itself biocompatible. The functional properties of TiNi wire are determined by the structure, composition, and thickness. The purpose of this work is to study the deformation behavior of thin TiNi wires depending on the thickness. TiNi wires of different thicknesses (40, 60, 90 µm) were tested by uniaxial tension to rupture and in the load-unload cycle (5 cycles). The results found that All TiNi wires exhibit the effect of superelasticity at a relative strain of 5-7%. With an increase in the wire thickness from 40 to 90 µm, the values of the martensitic shear stress increase from 450 to 1200 MPa and the tensile strength increases from 1300 to 3150 MPa.
ASTM F2129 Cyclic-Potentiodynamic Polarization Testing of Nitinol Stents Indicated for Use in the GI Tract
Authors: Walak Steven , Budiansky Noah 
Published: May 2022

Abstract
Nitinol self-expanding stents are used to treat disease in all areas of the human gastrointestinal (GI) tract. Chemistry along the GI tract changes both spatially and temporally with pH ranging from 1.2 in the stomach to 8.5 in the common bile duct. A variety of secretions add ions, digestive enzymes, and proteins to the environment along the GI tract. Establishing absolute acceptance criteria for corrosion resistance of metallic implants presents a unique challenge in this constantly changing environment. In this study, cyclic potentiodynamic polarization corrosion tests were conducted over several years at multiple labs in accordance with the requirements of ASTM F2129. Braided Nitinol wire stents with thermal oxide surface representing a range of GI tract stents with good clinical history were tested in solutions selected to simulate the target anatomy in the human gastrointestinal tract. The results suggest that acceptance criteria for devices tested in simulated vascular environments do not reflect requirements for successful devices used in the varied chemical environments of the GI tract. Breakdown voltage acceptance criterion need to consider the clinical application and in-body use environment. Inherent test variability must also be considered when demonstrating statistical equivalence to clinically successful comparator devices or fixed value specifications.
THE SIMULATION AND FEATURES OF COUNTERCURRENT FLOW IN VERTICAL CHANNELS OF CONTACT DEVICES
Authors: Kuzmenko I.M. 
Published: May 2022

The aim of the work is to study the modes of motion of the phases at the interface of the film of water-air flow in the vertical channel during the countercurrent motion of the phases of the coolant. To achieve this goal, the following problems are solved: for each of the phases, the stationary Navier-Stokes equations and continuity are recorded, taking into account the direction of gravity. The obtained system of equations in the two-dimensional formulation in cylindrical coordinates with corresponding boundary conditions is solved in the package COMSOL MULTIPHYSICS 5.6. In the specified package the modeling of the influence of factors on the behavior of the interface of the film water-air flow in the vertical channel during the countercurrent movement of the phases is carried out. It is concluded that the existence of concomitant flows at the interface of the phases, depending on the height of the channel and the flow of phases in the vertical channel.
As a result of the simulation, it was found that the countercurrent phases in the laminar mode in the vertical channel, the hydrodynamics at the interface of the phases differs in the height of the channel. At the inlet, at the bottom of the channel, the airflow creates a concomitant flow in the flowing film of water at the interface. Accordingly, at the top of the channel, at the inlet, the film of water creates a concomitant flow in the flow of wind, moving countercurrent. And in the canal itself, there is an area where the movement of water and air flows has no concomitant flows.
That is, as a result of simulation it was found that the countercurrent phases in the laminar mode in the vertical channel, the hydrodynamics at the phase boundary differs, depending on the zone at the height of the channel and three such zones.
Factors that affect the size of the above three zones are the height of the channel, flow rate, or speed of each of the phases. In particular, at the inlet of the water film into the channel with a speed = 0,3…1,1 m/s and a thickness of 0.25 mm (= 60… 210), the calculated value of the thickness of the concomitant airflow is (0.4 .. 1.6) 103 m and is directly proportional to the speed of the water film. Also, with a decrease in the height of the canal three times, from 0.150 to 0.050 m, the existence of three zones in the canal is maintained, but the height of the zone without concomitant flow decreases in direct proportion by one order - from 0.137 m to 0.0113 m.
The establishment of co-directed flows at the phase separation boundary in the channels of film contact devices for selection of the hydrodynamic regime to increase the efficiency of heat exchange.
Recognition of the variant type of spinal dural arteriovenous fistula: a rare but important consideration
Authors: O’Reilly Sean T. , Hendriks Eef Jacobus , Brunet Marie-Christine , Itsekson Ze’ev , Shahrani Rabab Al , Agid Ronit , Nicholson Patrick , terBrugge Karel , Radovanovic Ivan , Krings Timo 
Published: May 2022

OBJECTIVE
Spinal dural arteriovenous fistulas (SDAVFs) typically represent abnormal shunts between a radiculomeningeal artery and radicular vein, with the point of fistulization classically directly underneath the pedicle of the vertebral body, at the dural sleeve of the nerve root. However, SDAVFs can also develop in atypical locations or have more than one arterial feeder, which is a variant of SDAVF. The aim of this study was to describe the incidence and multidisciplinary treatment of variant SDAVFs in a single-center case series.

METHODS
Following institutional review board approval, the authors retrospectively analyzed their prospectively maintained database of patients with SDAVFs who presented between 2008 and 2020. For all patients, spinal digital subtraction angiograms were reviewed and variant SDAVFs were identified. Variant types of SDAVFs were defined as cases in which the fistulous point was not located underneath the pedicle. Patient demographics, angiographic features, clinical outcomes, and treatment modalities were assessed.

RESULTS
Of 59 patients with SDAVFs treated at the authors’ institution, 4 patients (6.8%) were identified as having a variant location of the shunt zone, pinpointed on the dura mater at the intervertebral level, further posteriorly within the spinal canal. In 3 cases (75%), a so-called bimetameric arterial supply was demonstrated.

CONCLUSIONS
Recognition of the variant type of SDAVF is crucial for management, as correct localization of the fistulous point and bimetameric supply are critical for successful surgical disconnection, preventing delay in achieving definitive treatment.
Socio-Economic Dimensions of the Economic Culture of Financial and Credit Specialists
Authors: Cherusheva H. B. , Parkhomenko V. V. 
Published: May 2022

Given the established market-based economic mechanisms in Ukraine, each specialist irrespective of his/her professional focus is required to have critical thinking, deep understanding of current socio-economic processes; competencies for team work, quick taking of innovative decisions in the conditions of uncertainty, business management in a company belonging to any ownership category or industry, data collection, processing and analysis.
The system of higher economic education is affected by formational change and macro-social factors: increasing globalization processes; development of open poly-cultural national and socio-economic practices of societal actors; access to the global information space; deepening integration of the higher education system and its harmonization with European and global standards.
A distinctive feature of our days is the increasingly rapid development of the economic education, giving evidence of the stably growing demand for economic specialties. But issues related with modernization of the higher school have remained on the agenda. One of them is the economic education system still resting on the grounds that are to a certain extent contradictory. First and foremost, it refers to a formalized approach to the implementation of European values and achievements of education systems in the practice of domestic higher education establishments (HEEs) without due consideration for domestic cultural specifics. Second, poor experiences of cooperation with Western partners, which hampers education processes based on Eurointegration. The gap between professional qualification of specialists and market demands, weak links of Ukrainian HEEs with external social and professional environments, and the mismatch between the professional readiness of specialists and labor market demands are factors complicating significantly job placements of post-graduates and decreasing their competitiveness.
The socio-economic realities of this day require high level of the economic culture with future specialists. A challenge of today is a specialist of new type with high level of professional fairness and responsibility (before society, profession or organization), able to intellectual and social initiative, creative communication, social and professional mobility.
The article highlights theoretical, methodological and practical issues of the economic culture and its contribution to the economy humanization. Socio-pedagogical problems of shaping the economic culture in future economists in the context of the existing system of economic education are outlined. The notion “economic culture” is analyzed from different methodological perspectives, the main factors for modernization of the economic education system in a way to shape the economic culture of students are substantiated. The economic culture is interpreted as a characteristic of a certain life style and a regulator of the economic behavior of specialists working in socio-economic fields.
Assessing the Impact of Education Quality on Economic Growth in OECD and CESEE Countries
Authors: Nazukova N. M. 
Published: May 2022

The retrospective data analysis concerning the level of per capita income evidenced that formation of an educated society created the precondition for the growth of labor productivity and economic growth. According to Gelor – Weil theory, in the 19th century, in Western Europe countries, as well as in the “Western outshoots” (the USA, Canada, Australia and New Zealand), there was a change in the attitude towards family planning, which consisted in preferring fewer well–educated children over a large number of uneducated ones. This made it possible to overcome the "Malthus trap" in these countries and enabled rapid rates of economic growth. Today, the total factor productivity of the United States is taken as a benchmark/frontier against which productivity in other countries is measured.
The article presents the results of assessing the impact of the quality of education, expressed by the "Skills" indicator of the Global Competitiveness Report, which characterizes the general level of skills of the labor force, as well as the quantity and quality of education in the country, on its total factor productivity. The assessment is based on the economic growth model of Ph. Agion and P. Howitt, which determines economic growth of a certain country by its’ human capital skills, as well as by the distance of such a country to the world technology frontier. The analysis presented in the article includes both OECD countries and CESEE countries, in particular Ukraine. Based on the results, it can be concluded that OECD countries, whose total factor productivities are a minimum 7 per cent above the world technology frontier, reached this – to the great extent – through better education. CESEE countries, whose total factor productivities are at least 59 per cent below the frontier (and Ukraine is among them), should improve the quality of education to get closer to the frontier.
Further analysis of the factors of education quality showed that government spending on education and quality of public and private institutions play great part in improving education both in CESEE and OECD countries. The proposed approach to assessing the factors of the quality of education can be used for further assessment of the impact of COVID–19 pandemic on the quality of education, as well as to justify the directions of state policy in the field of education aimed at ensuring economic recovery in the post–pandemic period.
The influence of the shape and size of dust fractions on their distribution and accumulation in mine workings when changing the structure of air flow
Authors: Smirnyakov Valery , Rodionov Vladimir , Smirnyakova Victoria , Orlov Fedor 
Published: May 2022

The results of the analysis of statistical data on accidents at Russian mines caused by explosions in the workings space have shown that explosions of methane-dust-air mixtures at underground coal mines are the most severe accidents in terms of consequences. A detailed analysis of literature sources showed that in the total number of explosions prevails total share of hybrid mixtures, i.e. with the simultaneous participation of gas (methane) and coal dust, as well as explosions with the possible or partial involvement of coal dust. The main causes contributing to the occurrence and development of dust-air mixture explosions, including irregular monitoring of by mine engineers and technicians of the schedule of dust explosion protective measures; unreliable assessment of the dust situation, etc., are given. The main problem in this case was the difficulty of determining the location and volume of dust deposition zones in not extinguished and difficult to access for instrumental control workings. Determination of the class-shape of coal dust particles is a necessary condition for constructing a model of the dust situation reflecting the aerosol distribution in the workings space. The morphological composition of coal mine dust fractions with dispersion less than 0.1 has been studied. Particle studies conducted using an LEICA DM 4000 optical microscope and IMAGE SCOPE M software made it possible to establish the different class-shapes of dust particles found in operating mines. It was found that the coal dust particles presented in the samples correspond to the parallelepiped shape to the greatest extent. The mathematical model based on the specialized ANSYS FLUENT complex, in which this class-form is incorporated, is used for predicting the distribution of explosive and combustible coal dust in the workings space. The use of the obtained model in production conditions will allow to determine the possible places of dust deposition and to develop measures to prevent the transition of coal dust from the aerogel state to the aerosol state and thereby prevent the formation of an explosive dust-air mixture.