bluuebunny/crossref_metadata_2025 huggingface dataset:
Solutions of Extension and Limits of Some Cantorian Paradoxes
Authors: Nescolarde-Selva Josué-Antonio , Usó-Doménech José-Luis , Segura-Abad Lorena , Alonso-Stenberg Kristian , Gash Hugh
Published: April 2020

Cantor thought of the principles of set theory or intuitive principles as universal forms that can apply to any actual or possible totality. This is something, however, which need not be accepted if there are totalities which have a fundamental ontological value and do not conform to these principles. The difficulties involved are not related to ontological problems but with certain peculiar sets, including the set of all sets that are not members of themselves, the set of all sets, and the ordinal of all ordinals. These problematic totalities for intuitive theory can be treated satisfactorily with the Zermelo and Fraenkel (ZF) axioms or the von Neumann, Bernays, and Gödel (NBG) axioms, and the iterative conceptions expressed in them.
Cloning, Secretory Expression and Characterization of a Unique pH-Stable and Cold-Adapted Alginate Lyase
Authors: Wang Zhi-Peng , Cao Min , Li Bing , Ji Xiao-Feng , Zhang Xin-Yue , Zhang Yue-Qi , Wang Hai-Ying
Published: April 2020

Cold-adapted alginate lyases have unique advantages for alginate oligosaccharide (AOS) preparation and brown seaweed processing. Robust and cold-adapted alginate lyases are urgently needed for industrial applications. In this study, a cold-adapted alginate lyase-producing strain Vibrio sp. W2 was screened. Then, the gene ALYW201 was cloned from Vibrio sp. W2 and expressed in a food-grade host, Yarrowia lipolytica. The secreted Alyw201 showed the activity of 64.2 U/mL, with a molecular weight of approximate 38.0 kDa, and a specific activity of 876.4 U/mg. Alyw201 performed the highest activity at 30 °C, and more than 80% activity at 25–40 °C. Furthermore, more than 70% of the activity was obtained in a broad pH range of 5.0–10.0. Alyw201 was also NaCl-independent and salt-tolerant. The degraded product was that of the oligosaccharides of DP (Degree of polymerization) 2–6. Due to its robustness and its unique pH-stable property, Alyw201 can be an efficient tool for industrial production.
Comparison of Post-Exercise Hypotension Responses in Paralympic Powerlifting Athletes after Completing Two Bench Press Training Intensities
Authors: Paz Ângelo de Almeida , Aidar Felipe José , de Matos Dihogo Gama , de Souza Raphael Fabrício , da Silva-Grigoletto Marzo Edir , van den Tillaar Roland , Ramirez-Campillo Rodrigo , Nakamura Fábio Yuzo , Costa Manoel da Cunha , Nunes-Silva Albená , Costa e Silva Anselmo de Athayde , Marçal Anderson Carlos , Reis Victor Machado
Published: April 2020

Background and objective: Post-exercise hypotension, the reduction of blood pressure after a bout of exercise, is of great clinical relevance. Resistance exercise training is considered an important contribution to exercise training programs for hypertensive individuals and athletes. In this context, post-exercise hypotension could be clinically relevant because it would maintain blood pressure of hypertensive individuals transiently at lower levels during day-time intervals, when blood pressure is typically at its highest levels. The aim of this study was to compare the post-exercise cardiovascular effects on Paralympic powerlifting athletes of two typical high-intensity resistance-training sessions, using either five sets of five bench press repetitions at 90% 1 repetition maximum (1RM) or five sets of three bench press repetitions at 95% 1RM. Materials and Methods: Ten national-level Paralympic weightlifting athletes (age: 26.1 ± 6.9 years; body mass: 76.8 ± 17.4 kg) completed the two resistance-training sessions, one week apart, in a random order. Results: Compared with baseline values, a reduction of 5–9% in systolic blood pressure was observed after 90% and 95% of 1RM at 20–50 min post-exercise. Furthermore, myocardial oxygen volume and double product were only significantly increased immediately after and 5 min post-exercise, while the heart rate was significantly elevated after the resistance training but decreased to baseline level by 50 min after training for both training conditions. Conclusions: A hypotensive response can be expected in elite Paralympic powerlifting athletes after typical high-intensity type resistance-training sessions.
Factors that Decrease Sedentary Behavior in Community-Dwelling Elderly People: A Longitudinal Study
Authors: Owari Yutaka
Published: April 2020

Background and objectives: This study was to clarify how the frequency of participation in a health class affected the reduction in sedentary behavior after two years, and whether decreases in sedentary behavior in elderly people who participated in a health class persisted two years after the end of an intervention. Materials and Methods: This study was longitudinal, and the results of a previous study conducted in 2017 were added to the findings of a different year. The participants were elderly health class members at a community dwelling in Japan who participated between 2016 and 2018. Of the 86 participants that were enrolled, the data of 80 were collected in 2016. A year later, in a 2017 follow-up, the number of participants was 80, and two years later, in a 2018 follow-up, there were 71 participants. Results: There was a significant difference with regards to the reduction of the sedentary behavior rate between two different groups (a health class participation rate of more than 75% and the other with less than 75%) two years later. However, no difference in sedentary behavior rate was found between the two groups (intervention group and control group) at a two-year follow-up, despite observing differences after one year. Conclusions: Continuous participation in a health class may help reduce sedentary behavior. After two years, “Active Guide” brochures and documents may not help in reducing sedentary behavior, despite seeing improvements after one year. Persistent social participation may have a more lasting effect than one-off interventions in reducing the sedentary behavior ratio.
Acupuncture for Relief of Gag Reflex in Patients Undergoing Transoesophageal Echocardiography—A Protocol for a Randomized Placebo-Controlled Trial
Authors: Usichenko Taras I. , Müller-Kozarez Irina , Knigge Stephan , Busch Raila , Busch Mathias
Published: April 2020

Background: Gagging during transesophageal echocardiography examination (TEE) can be distressing and even dangerous for patients. The needling of acupuncture point CV24 was described to be effective in reducing the gag reflex during TEE in patients with ischemic stroke or transient ischemic attack. Methods: We describe a proposal for a prospective, randomized, patient, practitioner and assessor-blinded, single-center trial with two arms/groups; real acupuncture will be compared to placebo acupuncture. A total of 60 (30 per group) patients scheduled for elective TEE in order to exclude a cardiac embolic source, endocarditis or for valve failure evaluation will be recruited according to patients’ selection criteria and receive either indwelling fixed intradermal needles at acupoints CV24 and bilateral PC6 or placebo needles at the same areas. Patients, the practitioners who will perform the TEE procedure, and the assessor of the outcome measures will be unaware of the group’s (real or placebo) allocation. Results: The primary outcome is the intensity of gagging, measured using verbal rating scale (VRS-11) from 0 = no gagging to 10 = intolerable gagging. Secondary outcomes include the incidence of gagging, the use of rescue medication, patients’ satisfaction with relief of unwanted side effects during TEE procedure, success of patients’ blinding (patients’ opinion to group allocation), heart rate and oxygen saturation measured by pulse oxymetry. Conclusions: To study the effects of acupuncture against gagging during TEE, we test the needling of acupoints CV24 and PC6 bilaterally. A placebo acupuncture is used for the control group. Trial registration number: NCT NCT0382142.
Enhancing the Separation Performance of Glassy PPO with the Addition of a Molecular Sieve (ZIF-8): Gas Transport at Various Temperatures
Authors: Benedetti Francesco M. , De Angelis Maria Grazia , Degli Esposti Micaela , Fabbri Paola , Masili Alice , Orsini Alessandro , Pettinau Alberto
Published: April 2020

In this study, we prepared and characterized composite films formed by amorphous poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and particles of the size-selective Zeolitic Imidazolate Framework 8 (ZIF-8). The aim was to increase the permselectivity properties of pure PPO using readily available materials to enable the possibility to scale-up the technology developed in this work. The preparation protocol established allowed robust membranes with filler loadings as high as 45 wt% to be obtained. The thermal, morphological, and structural properties of the membranes were analyzed via DSC, SEM, TGA, and densitometry. The gas permeability and diffusivity of He, CO2, CH4, and N2 were measured at 35, 50, and 65 °C. The inclusion of ZIF-8 led to a remarkable increase of the gas permeability for all gases, and to a significant decrease of the activation energy of diffusion and permeation. The permeability increased up to +800% at 45 wt% of filler, reaching values of 621 Barrer for He and 449 for CO2 at 35 °C. The ideal size selectivity of the PPO membrane also increased, albeit to a lower extent, and the maximum was reached at a filler loading of 35 wt% (1.5 for He/CO2, 18 for CO2/N2, 17 for CO2/CH4, 27 for He/N2, and 24 for He/CH4). The density of the composite materials followed an additive behavior based on the pure values of PPO and ZIF-8, which indicates good adhesion between the two phases. The permeability and He/CO2 selectivity increased with temperature, which indicates that applications at higher temperatures than those inspected should be encouraged.
Recovering Lithium from the Cathode Active Material in Lithium-Ion Batteries via Thermal Decomposition
Authors: Kuzuhara Shunsuke , Ota Mina , Tsugita Fuka , Kasuya Ryo
Published: April 2020

In this study, calcination tests were performed on a mixed sample of lithium cobalt oxide and activated carbon at 300–1000 °C under an argon atmosphere. The tests were conducted to discover an effective method for recovering lithium and cobalt from the cathode active material used in lithium-ion batteries. Additionally, the effect of soluble fluorine on the purification of lithium carbonate was investigated by the addition of lithium fluoride to an aqueous lithium hydroxide solution and a CO2 flow test was performed. The lithium recovery was ≥90% when the calcination occurred at temperatures of 500–600 °C. However, the percent recovery decreased at temperatures ≥700 °C. It was demonstrated that in order to increase the recovery while maintaining 99% purity of lithium carbonate in the recovered material, it was imperative to increase the temperature of the solution and to limit the F/Li ratio (mass%/mass%) in the solution to a value that did not exceed 0.05.
Review on the Effect of Deep Cryogenic Treatment of Metallic Materials in Automotive Applications
Authors: Jovičević-Klug Patricia , Podgornik Bojan
Published: April 2020

With the development of society, every year there are increasing demands in the automotive industry on cost savings, environmental safety, reduction of raw material consumption, performance improvement, material life cycle and recycling of components. In this review, emphasis is given on ferrous and non-ferrous alloys, which are used as components, where both groups can be treated by deep cryogenic treatment (DCT). DCT has shown to increase hardness, tensile strength and wear resistance, reduce density of defects in crystal structure, improve toughness and corrosion resistance. Though, some researchers also reported results that showed no change in material properties, or even deterioration of material properties, when subjected to DCT. This additionally points out to lack of consistency and reliability of the DCT process, which is needed for its successful incorporation in automotive applications. However, to prove with certainty the resulting outcome on the material properties and knowledge about the reasons for the variation of this effect on metallic materials, further approach and testing with different variables should be conducted in the future. This review provides a synopsis of different approaches of DCT on different materials for automotive applications in order to indicate effects on the material performance during DCT.
A Comparative Study of Analytical Rosenthal, Finite Element, and Experimental Approaches in Laser Welding of AA5456 Alloy
Authors: Hekmatjou Hamidreza , Zeng Zhi , Shen Jiajia , Oliveira J. P. , Naffakh-Moosavy Homam
Published: April 2020

The thermal regime and microstructural phenomenon are studied by using finite-element (FE) modelling and the analytical Rosenthal equation during laser welding of aluminum alloy 5456 (AA5456) components. A major goal is to determine the merits and demerits of this analytical equation which can be an alternative to FE analysis, and to evaluate the effect of imperative assumptions on predicted consequences. Using results from the analytical and numerical approaches in conjunction with experiments, different physical features are compared. In this study, the results obtained from experiments in terms of melt pool shapes are compared with the predicted ones achieved from the numerical and analytical approaches in which the FE model is more accurate than the Rosenthal equation in the estimation of the melt pool dimensions. Furthermore, as to the partially melted zones, the estimations achieved from the numerical modeling are more genuine than ones from the analytical equation with regards to the experimental results. At high energy density, near keyhole welding mode, the reported results show that experimental melt widths are supposed to be narrower than the fusion widths estimated by the analytical solution. The primary explanation could be the influence of thermal losses that occurred during convection and radiation, which are neglected in the Rosenthal equation. Additionally, the primary dendrite arm spacing (PDAS) estimated with the numerical modeling and the analytical Rosenthal solution is comparable with the experimental results obtained.
Tuning the Morphology and Properties of Nanostructured Cu-ZnO Thin Films Using a Two-Step Sputtering Technique
Authors: Lee Jae-Ho , Oh Kwonwoo , Jung Kyungeun , Wilson K.C. , Lee Man-Jong
Published: April 2020

Zinc oxide (ZnO) is a wide-band-gap semiconductor that is promising for use as a transparent conductive oxide film. To date, to improve their optoelectrical properties, pristine ZnO films have been doped with metals using various techniques. In this study, nanostructured Cu-ZnO thin films were synthesized using a modified two-step radio frequency magnetron sputtering technique with separate ZnO and metallic Cu targets. Controlling the timing of the Cu/ZnO co-sputtering and ZnO-only sputtering steps afforded a significant change in the resulting nanostructures, such as uniform Cu-ZnO and broccoli-structured Cu-ZnO thin films. Using various measurement techniques, the influence of Cu doping was analyzed in detail. Furthermore, a crystal growth model for the formation of the broccoli-like clusters was suggested. The Cu-ZnO thin films synthesized using this technique demonstrate a highly improved conductivity with some loss in optical transmittance.
Study and Characterization of EN AW 6181/6082-T6 and EN AC 42100-T6 Aluminum Alloy Welding of Structural Applications: Metal Inert Gas (MIG), Cold Metal Transfer (CMT), and Fiber Laser-MIG Hybrid Comparison
Authors: Cornacchia Giovanna , Cecchel Silvia
Published: April 2020

The present research investigates the effects of different welding techniques, namely traditional metal inert gas (MIG), cold metal transfer (CMT), and fiber laser-MIG hybrid, on the microstructural and mechanical properties of joints between extruded EN AW 6181/6082-T6 and cast EN AC 42100-T6 aluminum alloys. These types of weld are very interesting for junctions of Al-alloys parts in the transportation field to promote the lightweight of a large scale chassis. The weld joints were characterized through various metallurgical methods including optical microscopy and hardness measurements to assess their microstructure and to individuate the nature of the intermetallics, their morphology, and distribution. The results allowed for the evaluation of the discrepancies between the welding technologies (MIG, CMT, fiber laser) on different aluminum alloys that represent an exhaustive range of possible joints of a frame. For this reason, both simple bar samples and real junctions of a prototype frame of a sports car were studied and, compared where possible. The study demonstrated the higher quality of innovative CMT and fiber laser-MIG hybrid welding than traditional MIG and the comparison between casting and extrusion techniques provide some inputs for future developments in the automotive field.
Characterization of Influences of Steel-Aluminum Dissimilar Joints with Intermediate Zinc Layer
Authors: Bick Tobias , Heuler Verena , Treutler Kai , Wesling Volker
Published: April 2020

Brittle intermetallic phases are formed when steel and aluminum are joined. Therefore, it is difficult to use this combination of materials when applying the multimaterial design in the construction of load-adapted and weight-adapted structures. In order to largely avoid the formation of these brittle phases, joining processes based on diffusion processes, such as composite forging, depict a good solution approach. The materials are joined in a solid state. Furthermore, zinc additives are used to create the joint. Zinc forms a compound with both steel and aluminum without the formation of brittle phases. By combining the composite forging process with zinc additives, strength values of 26 N/mm2 can be reached. This is higher, in comparison to former investigations of resistance spot welded and clinched joints. The joint properties depend on the composition of the zinc interlayer. Small amounts of magnesium in the zinc interlayer affected the strength and ductility values. While the strength decreased by about 30% in contrast to the zinc layer without magnesium, the ductility increased by 60%. This effect was probably due to the metallurgical impact of the alloying elements on phase formation, as could be shown by energy dispersive X-ray spectroscopy (EDX) analyses of the joint zones. Thereby, it was shown that the brittle intermetallic phases are located only in small areas.
Crystallization Process and Microstructural Evolution of Melt Spun Al-RE-Ni-(Cu) Ribbons
Authors: Cuevas Francisco G. , Lozano-Perez Sergio , Aranda Rosa María , Astacio Raquel
Published: April 2020

The crystallization process, both at the initial and subsequent stages, of amorphous Al88-RE4-Ni8 alloys (RE = Y, Sm and Ce) has been studied. Additionally, the consequences of adding 1 at.% Cu replacing Ni or Al were studied. The stability of the amorphous structure in melt spun ribbons was thermally studied by differential scanning calorimetry, with Ce alloys being the most stable. The effect of Cu to reduce the nanocrystal size during primary crystallization was analyzed by transmission electron microscopy. This latter technique and x-ray diffraction showed the formation of intermetallic phases at higher temperatures. A clear difference was observed for the Ce alloy, with a simpler sequence involving the presence of Al3Ni and Al11Ce3. However, for the Y and Sm alloys, a more complex evolution involving metastable ternary phases before Al19RE5Ni3 appears, takes place. The shape of the intermetallics changes from equiaxial in the Ce alloys to elongate for Y and Sm, with longer particles for Sm and, in general, when Cu is added to the alloy.
Using DEFORM Software for Determination of Parameters for Two Fracture Criteria on DIN 34CrNiMo6
Authors: Poláková Ivana , Zemko Michal , Rund Martin , Džugan Ján
Published: April 2020

The aim of this study was to calibrate a material model with two fracture criteria that is available in the DEFORM software on DIN 34CrNiMo6. The purpose is to propose a type of simple test that will be sufficient for the determination of damage parameters. The influence of the quantity of mechanical tests on the accuracy of the fracture criterion was explored. This approach was validated using several tests and simulations of damage in a tube and a round bar. These tests are used in engineering applications for their ease of manufacturing and their strong ability to fracture. The prediction of the time and location of the failure was based on the parameters of the relevant damage model. Normalized Cockroft-Latham and Oyane criteria were explored. The validation involved comparing the results of numerical simulation against the test data. The accuracy of prediction of fracture for various stress states using the criteria was evaluated. Both fracture criteria showed good agreement in terms of the fracture locus, but the Oyane criterion proved more suitable for cases covering larger triaxiality ranges.
A Comparison of the Ballistic Performances of Various Microstructures in MIL-A-12560 Armor Steel
Authors: Konca Erkan
Published: April 2020

Due to their advantageous properties, there is a growing interest in developing armor steels containing fully or partially bainitic microstructures. In this study, bainitic and martensitic microstructures were obtained in rolled homogeneous armor (RHA) steel samples and their ballistic protection performances were investigated. RHA (MIL-A-12560) steel samples were subjected to isothermal heat treatments at three different temperatures, where one temperature (360 °C) was above the martensite formation start (Ms) temperature of 336 °C while the other two (320 °C and 270 °C) were below. For the assessment of the ballistic protection performance, the kinetic energy losses of the 12.7 mm bullets fired at the test samples were determined. The promising nature of the bainite microstructure was confirmed as the sample isothermally treated at 360 °C provided approximately 10% higher ballistic protection as compared to the regular RHA sample of tempered martensite microstructure. However, the ballistic performances of the isothermally treated samples decreased as the treatment temperature went below the Ms temperature. Following the ballistic tests, hardness measurements, impact tests at −40 °C, and macro- and microstructural examinations of the samples were performed. No correlation was found between the hardness and impact energies of the samples and their ballistic performances.
Laboratory X-ray Diffraction Complex for In Situ Investigations of Structural Phase Evolution of Materials under Gaseous Atmosphere
Authors: Syrtanov Maxim , Garanin Georgiy , Kashkarov Egor , Pushilina Natalia , Kudiiarov Viktor , Murashkina Tatyana
Published: April 2020

In this work, a laboratory X-ray diffraction complex for in situ investigations of structural phase evolution of materials under gaseous atmosphere and elevated temperatures was developed. The approbation of the complex was carried out using a commercially pure titanium (CP-Ti) powder, zirconium (Zr-1Nb) alloy and electron beam melted Ti-6Al-4V alloy. It was established that hydrogenation of the CP-Ti powder occurred at a temperature of 500 °C and a hydrogen pressure of 0.5 atm, accompanied by the formation of metastable γ titanium hydride (γ-TiH) phase. The lifetime of the γ-TiH phase was 35–40 min. Decomposition of the γ-TiH occurred after reaching a temperature of 650 °C as a result of the thermally stimulated desorption of hydrogen. The α-Zr → δ-ZrH phase transformation was observed under hydrogenation of the zirconium Zr-1Nb alloy at a temperature of 350 °C and a hydrogen pressure of 0.5 atm. It was revealed that the increase in hydrogenation temperature to 450 °C accelerated this transformation by two times. Hydrogenation of the electron beam melted titanium Ti-6Al-4V alloy at a temperature of 650 °C and hydrogen pressure of 0.5 atm was accompanied by the α → α + β → β + α2 phase transformations.
A Comparative Study of Green Inhibitors for Galvanized Steel in Aqueous Solutions
Authors: Alar Vesna , Stojanović Ivan , Mezdić Dražen
Published: April 2020

This study investigates the morphology, composition and corrosion resistance of hot dip galvanized (HDG) steel bolts in fresh water, 1% NaCl saltwater in the presence of protective compounds L-Tryptophan and three conventional corrosion inhibitors: Inhibitor 1-VCI (amine-carboxylates-based), Inhibitor 2 (based on carboxylate acid), and Inhibitor 3 (water-based, carboxylate acid). Quantitative tests performed include gravimetric analysis and electrochemical techniques, such as linear polarization, Tafel extrapolation, and Electrochemical Impedance Spectroscopy (EIS). Electrochemical measurements determined the polarization resistance Rp, corrosion rate vcorr, and corrosion potential Ecorr. Furthermore, Scanning Electron Microscopy (SEM) and ATR-FTIR spectrometry were used to evaluate and characterize the formed layers on the surface of hot-dip galvanized steel samples. The results reveal that upon corrosion new compounds are formed onto the exposed areas of the treated bolts such as zinc-carbonates, zinc-hydroxides, etc. The presence of these compounds on the surface of the HDG steel bolts hinders the corrosion process by reducing the rate of the anodic and cathodic reactions. The gravimetric test showed that L-tryptophan in distilled water has mass increase, resulting from the formation of white deposits on the sample surface. In fresh water and distilled water, the best corrosion resistance was achieved with Inhibitor 1-VCI, while L-tryptophan showed best results in 1% NaCl solution.
In Vitro and In Vivo Study of Titanium Grade IV and Titanium Grade V Implants with Different Surface Treatments
Authors: Diaz-Sanchez Rosa-Maria , de-Paz-Carrion Alvaro , Serrera-Figallo Maria-Angeles , Torres-Lagares Daniel , Barranco Angel , León-Ramos Juan-Rey , Gutierrez-Perez Jose-Luis
Published: April 2020

The aim of our study is to evaluate different implant surface treatments using TiIV and TiV in in vitro and in vivo studies. An in vitro study was established comprising four study groups with treated and untreated TiIV titanium discs (TiIVT and TiIVNT) and treated and untreated TiV titanium discs (TiVT and TiVNT). The surface treatment consisted in a grit blasting treatment with alumina and double acid passivation to modify surface roughness. The surface chemical composition and the surface microstructure of the samples were analyzed. The titanium discs were subjected to cell cultures to determine cell adhesion and proliferation of osteoblasts on them. The in vivo study was carried out on the tibia of three New Zealand rabbits in which 18 implants divided into three experimental groups were placed (TiIVT, TiIVNT, and TiVT). Micro-computed tomography (micro-CT) was performed to determine bone density around the implants. The results showed that cell culture had minor adhesion and cell proliferation in TiIVT and TiVT within the first 6 and 24 h. However, no differences were found after 48 h. No statistically significant differences were found in the in vivo micro-CT and histological study; however, there was a positive trend in bone formation in the groups with a treated surface. Conclusions: All groups showed a similar response to in vitro cell proliferation cultures after 48 h. No statistically significant differences were found in the in vivo micro-CT and histological study.
Multi-Aspects Optimization of Process Parameters in CNC Turning of LM 25 Alloy Using the Taguchi-Grey Approach
Authors: Dhanalakshmi S. , Rameshbabu T.
Published: April 2020

LM 25 is an aluminum alloy that has numerous applications such as in the manufacturing of automobile components and food industries, and especially in marine and seawater applications, due to its exceptional properties. An exertion has been taken for attaining the best-suited group of machining variables to attain improved and better performance in machining such as increased rate of material removal, lessened roughness values at the machined surface and the total cost incurred during machining. Taguchi’s design methodology has been implemented for devising the experimental combinations and also for single aspects optimization of deemed performance measures. Grey’s theory concept has been adopted for attaining Grey Relational Coefficient values and the values have been further utilized for evolving Grey Relational Grade. Analysis of Variance (ANOVA) has been employed to determine the significance of input process variables on the desired performance measures and interaction analysis also has been performed to determine the interaction effect between the selected process variables. As a result of optimization, the optimal combination of cutting parameters in turning LM25 aluminum alloy is cutting speed (A) = 150.79 m/min, feed (B) = 0.15 mm/min, depth of cut (C) = 0.9 mm and cutting fluid flow rate (D) = 75 mL/h. Compared with the initial parameter settings, surface roughness (Ra) decreases by 67.97%, material removal rate (MRR) increases by 88.12% and total machining cost (TMC) decreases by 93.86%. The proposed approach helps the manufacturer to attain better machining performance at an affordable cost.
Influences of a Hot-Working Process on the Microstructural Evolution and Creep Performance of a Spray-Formed Nickel-Based Superalloy
Authors: Tian Tian , Ge Changchun , Li Xinggang , Hao Zhibo , Peng Shiqing , Jia Chonglin
Published: April 2020

A new third generation nickel-based powder metallurgy (PM) superalloy, designated as FGH100L, was prepared by spray forming. The effects of hot isostatic pressing (HIP) and isothermal forging (IF) processes on the creep performance, microstructure, fracture, and creep deformation mechanism of the alloy were studied. The microstructure and fracture were characterized by optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The coupled HIP and IF process improved the creep performance of the alloy under the creep condition of 705 °C/897 MPa. As for both the HIPed and IFed alloys, the creep process was dominated by the accumulation of dislocations and stacking faults, cutting through γ′ precipitates. The microstructural evolution was the main factor affecting the creep performance, which mainly manifested as coarsening, splitting, and morphology change of γ′ precipitates. Both the creep fractures of the HIPed and IFed alloys indicated intergranular fracture characteristics. In the former, wedge-shaped cracks usually initiated at the trigeminal intersection of the grain boundaries, while in the latter, cavity cracks generate more easily around the serrated curved grain boundary and carbides.
Corrosion and Protection of Metals
Authors: Bastidas David M.
Published: April 2020

During the last few decades, an enormous effort has been made to understand corrosion phenomena and their mechanisms, and to elucidate the causes that dramatically influence the service lifetime of metal materials [...]
Editorial for the Special Issue on 3D Printing for Tissue Engineering and Regenerative Medicine
Authors: Serpooshan Vahid , Guvendiren Murat
Published: April 2020

Three-dimensional (3D) bioprinting uses additive manufacturing techniques to fabricate 3D structures consisting of heterogenous selections of living cells, biomaterials, and active biomolecules [...]
Step-Wise Deposition Process for Dielectrophoretic Formation of Conductive 50-Micron-Long Carbon Nanotube Bridges
Authors: Zhou Tuo , Kropp Ethan , Chen Jingyuan , Kulinsky Lawrence
Published: April 2020

Carbon Nanotube (CNT) agglomerates can be aligned along field lines between adjacent electrodes to form conductive bridges. This study discusses the step-wise process of dielectrophoretic deposition of CNTs to form conducting bridges between adjacent electrodes. For the first time, the creation of conductive CNT bridges spanning lengths over 50 microns is demonstrated. The CNT bridges are permanently secured using electrodeposition of the conducting polymer polypyrrole. Morphologies of the CNT bridges formed within a frequency range of 1 kHz and 10 MHz are explored and explained as a consequence of interplay between dielectrophoretic and electroosmotic forces. Postdeposition heat treatment increases the conductivity of CNT bridges, likely due to solvent evaporation and resulting surface tension inducing better contact between CNTs.
Design and Testing of Bistable Lattices with Tensegrity Architecture and Nanoscale Features Fabricated by Multiphoton Lithography
Authors: Vangelatos Zacharias , Micheletti Andrea , Grigoropoulos Costas P. , Fraternali Fernando
Published: April 2020

A bistable response is an innate feature of tensegrity metamaterials, which is a conundrum to attain in other metamaterials, since it ushers unconventional static and dynamical mechanical behaviors. This paper investigates the design, modeling, fabrication and testing of bistable lattices with tensegrity architecture and nanoscale features. First, a method to design bistable lattices tessellating tensegrity units is formulated. The additive manufacturing of these structures is performed through multiphoton lithography, which enables the fabrication of microscale structures with nanoscale features and extremely high resolution. Different modular lattices, comprised of struts with 250 nm minimum radius, are tested under loading-unloading uniaxial compression nanoindentation tests. The compression tests confirmed the activation of the designed bistable twisting mechanism in the examined lattices, combined with a moderate viscoelastic response. The force-displacement plots of the 3D assemblies of bistable tensegrity prisms reveal a softening behavior during the loading from the primary stable configuration and a subsequent snapping event that drives the structure into a secondary stable configuration. The twisting mechanism that characterizes such a transition is preserved after unloading and during repeated loading-unloading cycles. The results of the present study elucidate that fabrication of multistable tensegrity lattices is highly feasible via multiphoton lithography and promulgates the fabrication of multi-cell tensegrity metamaterials with unprecedented static and dynamic responses.
Role of Vitamin D in Preventing and Treating Selected Extraskeletal Diseases—An Umbrella Review
Authors: Maretzke Friederike , Bechthold Angela , Egert Sarah , Ernst Jana B. , Melo van Lent Debora , Pilz Stefan , Reichrath Jörg , Stangl Gabriele I. , Stehle Peter , Volkert Dorothee , Wagner Michael , Waizenegger Julia , Zittermann Armin , Linseisen Jakob
Published: April 2020

Evidence is accumulating that vitamin D may have beneficial effects on respiratory tract, autoimmune, neuro-degenerative, and mental diseases. The present umbrella review of systematic reviews (SRs) of cohort studies and randomised controlled trials (RCTs), plus single Mendelian randomisation studies aims to update current knowledge on the potential role of vitamin D in preventing and treating these extraskeletal diseases. Altogether, 73 SRs were identified. Observational data on primary prevention suggest an inverse association between vitamin D status and the risk of acute respiratory tract infections (ARI), dementia and cognitive decline, and depression, whereas studies regarding asthma, multiple sclerosis (MS), and type 1 diabetes mellitus (T1DM) are scarce. SRs of RCTs support observational data only for the risk of ARI. No respective RCTs are available for the prevention of chronic obstructive pulmonary disease (COPD), MS, and T1DM. SRs of RCTs indicate beneficial therapeutic effects in vitamin D-deficient patients with asthma and COPD, while effects on major depression and T1DM need to be further elucidated. Mendelian randomisation studies do not consistently support the results of SRs. Since several limitations of the included SRs and existing RCTs do not permit definitive conclusions regarding vitamin D and the selected diseases, further high-quality RCTs are warranted.
“An Important Part of Who I am”: The Predictors of Dietary Adherence among Weight-Loss, Vegetarian, Vegan, Paleo, and Gluten-Free Dietary Groups
Authors: Cruwys Tegan , Norwood Rebecca , Chachay Veronique S. , Ntontis Evangelos , Sheffield Jeanie
Published: April 2020

Weight-loss diets are notorious for their low adherence, which is a barrier to efforts to reduce population rates of overweight and obesity. However, there is some evidence that adherence is better among people on other kinds of diets, such as vegan and gluten free. This study aimed to explore the predictors of dietary adherence across five restrictive dietary patterns (vegan, vegetarian, paleo, gluten free, and weight loss). This study used both qualitative and quantitative methods among 292 adult community members who were following a restrictive dietary pattern. Personality, mental health, and motivational predictors of adherence were examined. Substantial differences in adherence were found between dietary groups, with vegans and vegetarians being particularly high in adherence and gluten-free and weight-loss dieters being comparably low. Four consistent predictors of adherence across different dietary patterns were supported in both the quantitative and qualitative analyses. Self-efficacy and social identification with one’s dietary group positively predicted adherence. Conversely, being motivated in one’s dietary choices by mood or by weight control negatively predicted adherence. These findings speak to the importance of social and motivational factors in determining adherence. The results also illustrate the utility of looking beyond weight-loss dieters and virtuous individual traits for insights into how adherence may be improved.
Effective Field Theories
Authors: Grozin Andrey
Published: April 2020

This paper represents a pedagogical introduction to low-energy effective field theories. In some of them, heavy particles are “integrated out” (a typical example—the Heisenberg–Euler EFT); in some, heavy particles remain but some of their degrees of freedom are “integrated out” (Bloch–Nordsieck EFT). A large part of these lectures is, technically, in the framework of QED. QCD examples, namely decoupling of heavy flavors and HQET, are discussed only briefly. However, effective field theories of QCD are very similar to the QED case, and there are just some small technical complications: more diagrams, color factors, etc. The method of regions provides an alternative view at low-energy effective theories; this is also briefly introduced.
Multi-Label Learning based Semi-Global Matching Forest
Authors: Xia Yuanxin , d’Angelo Pablo , Tian Jiaojiao , Fraundorfer Friedrich , Reinartz Peter
Published: April 2020

Semi-Global Matching (SGM) approximates a 2D Markov Random Field (MRF) via multiple 1D scanline optimizations, which serves as a good trade-off between accuracy and efficiency in dense matching. Nevertheless, the performance is limited due to the simple summation of the aggregated costs from all 1D scanline optimizations for the final disparity estimation. SGM-Forest improves the performance of SGM by training a random forest to predict the best scanline according to each scanline’s disparity proposal. The disparity estimated by the best scanline acts as reference to adaptively adopt close proposals for further post-processing. However, in many cases more than one scanline is capable of providing a good prediction. Training the random forest with only one scanline labeled may limit or even confuse the learning procedure when other scanlines can offer similar contributions. In this paper, we propose a multi-label classification strategy to further improve SGM-Forest. Each training sample is allowed to be described by multiple labels (or zero label) if more than one (or none) scanline gives a proper prediction. We test the proposed method on stereo matching datasets, from Middlebury, ETH3D, EuroSDR image matching benchmark, and the 2019 IEEE GRSS data fusion contest. The result indicates that under the framework of SGM-Forest, the multi-label strategy outperforms the single-label scheme consistently.
The Delineation and Grading of Actual Crop Production Units in Modern Smallholder Areas Using RS Data and Mask R-CNN
Authors: Lv Yahui , Zhang Chao , Yun Wenju , Gao Lulu , Wang Huan , Ma Jiani , Li Hongju , Zhu Dehai
Published: April 2020

The extraction and evaluation of crop production units are important foundations for agricultural production and management in modern smallholder regions, which are very significant to the regulation and sustainable development of agriculture. Crop areas have been recognized efficiently and accurately via remote sensing (RS) and machine learning (ML), especially deep learning (DL), which are too rough for modern smallholder production. In this paper, a delimitation-grading method for actual crop production units (ACPUs) based on RS images was explored using a combination of a mask region-based convolutional neural network (Mask R-CNN), spatial analysis, comprehensive index evaluation, and cluster analysis. Da’an City, Jilin province, China, was chosen as the study region to satisfy the agro-production demands in modern smallholder areas. Firstly, the ACPUs were interpreted from perspectives such as production mode, spatial form, and actual productivity. Secondly, cultivated land plots (C-plots) were extracted by Mask R-CNN with high-resolution RS images, which were used to delineate contiguous cultivated land plots (CC-plots) on the basis of auxiliary data correction. Then, the refined delimitation-grading results of the ACPUs were obtained through comprehensive evaluation of spatial characteristics and real productivity clustering. For the conclusion, the effectiveness of the Mask R-CNN model in C-plot recognition (loss = 0.16, mean average precision (mAP) = 82.29%) and a reasonable distance threshold (20 m) for CC-plot delimiting were verified. The spatial features were evaluated with the scale-shape dimensions of nine specific indicators. Real productivities were clustered by the incorporation of two-step cluster and K-Means cluster. Furthermore, most of the ACPUs in the study area were of a reasonable scale and an appropriate shape, holding real productivities at a medium level or above. The proposed method in this paper can be adjusted according to the changes of the study area with flexibility to assist agro-supervision in many modern smallholder regions.
Individual Tree Crown Segmentation of a Larch Plantation Using Airborne Laser Scanning Data Based on Region Growing and Canopy Morphology Features
Authors: Ma Zhenyu , Pang Yong , Wang Di , Liang Xiaojun , Chen Bowei , Lu Hao , Weinacker Holger , Koch Barbara
Published: April 2020

The detection of individual trees in a larch plantation could improve the management efficiency and production prediction. This study introduced a two-stage individual tree crown (ITC) segmentation method for airborne light detection and ranging (LiDAR) point clouds, focusing on larch plantation forests with different stem densities. The two-stage segmentation method consists of the region growing and morphology segmentation, which combines advantages of the region growing characteristics and the detailed morphology structures of tree crowns. The framework comprises five steps: (1) determination of the initial dominant segments using a region growing algorithm, (2) identification of segments to be redefined based on the 2D hull convex area of each segment, (3) establishment and selection of profiles based on the tree structures, (4) determination of the number of trees using the correlation coefficient of residuals between Gaussian fitting and the tree canopy shape described in each profile, and (5) k-means segmentation to obtain the point cloud of a single tree. The accuracy was evaluated in terms of correct matching, recall, precision, and F-score in eight plots with different stem densities. Results showed that the proposed method significantly increased ITC detections compared with that of using only the region growing algorithm, where the correct matching rate increased from 73.5% to 86.1%, and the recall value increased from 0.78 to 0.89.
A Novel UAV-Assisted Positioning System for GNSS-Denied Environments
Authors: Partsinevelos Panagiotis , Chatziparaschis Dimitrios , Trigkakis Dimitrios , Tripolitsiotis Achilleas
Published: April 2020

Global Navigation Satellite Systems (GNSS) are extensively used for location-based services, civil and military applications, precise time reference, atmosphere sensing, and other applications. In surveying and mapping applications, GNSS provides precise three-dimensional positioning all over the globe, day and night, under almost any weather conditions. The visibility of the ground receiver to GNSS satellites constitutes the main driver of accuracy for GNSS positioning. When this visibility is obstructed by buildings, high vegetation, or steep slopes, the accuracy is degraded and alternative techniques have to be assumed. In this study, a novel concept of using an unmanned aerial system (UAS) as an intermediate means for improving the accuracy of ground positioning in GNSS-denied environments is presented. The higher elevation of the UAS provides a clear-sky visibility line towards the GNSS satellites, thus its accuracy is significantly enhanced with respect to the ground GNSS receiver. Thus, the main endeavor is to transfer the order of accuracy of the GNSS on-board the UAS to the ground. The general architecture of the proposed system includes hardware and software components (i.e., camera, gimbal, range finder) for the automation of the procedure. The integration of the coordinate systems for each payload setting is described, while an error budget analysis is carried out to evaluate and identify the system’s critical elements along with the potential of the proposed method.
Use of Uncertainty Inflation in OSTIA to Account for Correlated Errors in Satellite-Retrieved Sea Surface Temperature Data
Authors: Reid Rebecca , Good Simon , Martin Matthew J.
Published: April 2020

Sea surface temperature (SST) analysis systems such as the Operational Sea Surface Temperature and Ice Analysis (OSTIA) use statistical methods to combine observations together with a first guess field to create spatially complete maps of SST. These commonly assume that observation errors are uncorrelated, yet some errors (such as due to retrieval issues) can be correlated. Information about errors is used by the analysis system to determine the weighting to apply to the observations, hence this incorrect assumption could degrade the analysis. A common technique to mitigate for this is to inflate the observation uncertainties. Using information on observation error correlations provided with data produced by the European Space Agency (ESA) SST Climate Change Initiative (CCI) project, idealised tests were carried out to determine how this inflation technique can best be applied. These showed that applying inflation in situations where the observation errors are correlated over similar or larger distances to the errors in the background can cause unpredictable and sometimes negative results. However, in situations where the observation error correlation length scale is relatively small, inflation should improve the analysis. These findings were adapted to the OSTIA system and various configurations were tested. It was found that the inflation methods did not affect statistics of differences between the analyses and independent Argo reference data. However, the SST gradients were affected, particularly if some observation uncertainties were inflated but others were not. The results from both the idealised tests and the application to the real system therefore highlight that it is challenging to implement the inflation method in the case of an SST analysis system and show the need for assimilation schemes that can make full use of observation error correlation information.