bluuebunny/crossref_metadata_2025 huggingface dataset:
Anti-Thyroid Peroxidase and Anti-Thyroglobulin Autoantibodies in the Cerebrospinal Fluid of Patients with Unipolar Depression
Authors: Dersch Rick , Tebartz van Elst Ludger , Hochstuhl Benedikt , Fiebich Bernd L. , Stich Oliver , Robinson Tilman , Matysik Miriam , Michel Maike , Runge Kimon , Nickel Kathrin , Domschke Katharina , Endres Dominique
Published: July 2020

Introduction: The risk of developing depression is increased in patients with autoimmune thyroiditis. Autoimmune Hashimoto thyroiditis is diagnosed using the serum markers anti-thyroid peroxidase (TPO) and anti-thyroglobulin (TG) antibodies. In rare cases, patients with autoimmune thyroiditis can also suffer from the heterogeneous and ill-defined syndrome of Hashimoto encephalopathy. Biomarkers for Hashimoto encephalopathy or for any brain involvement of autoimmune thyroiditis are currently lacking. The aim of the present descriptive study was therefore to determine whether a subgroup of seropositive patients shows intrathecal anti-thyroid antibody synthesis in the cerebrospinal fluid (CSF). Participants and methods: Paired serum and CSF samples from 100 patients with unipolar depression were examined for anti-TPO and anti-TG antibodies using enzyme-linked immunosorbent assays. Antibody-specific indices (ASIs) were calculated for seropositive samples. These ASIs allow the differentiation between the brain-derived fraction of antibodies and antibodies which are passively diffused from the serum. ASIs >1.4 were assessed as positive for brain-derived antibodies. Additionally, for explorative evaluations, a stricter ASI limit of >2 was applied. Results: Anti-TPO antibodies were increased in the serum of 16 patients (16%); increased anti-TPO ASIs (>1.4) were detected in 11 of these patients (69%). Anti-TG antibodies in the serum were detected in three patients (3%), with two of them (67%) showing increased ASIs (>1.4). Overall, the authors found increased anti-thyroid antibodies in 17 of 100 patients (17%), with 13 out of 17 patients showing increased ASIs (76%; range 1.4–4.1). Choosing ASI levels of >2 led to positive findings in six out of 16 patients (38%) with anti-TPO antibodies in their serum but no increase in ASIs in three patients (0%) who were seropositive for anti-TG antibodies. The patients with elevated ASIs (N = 13) were younger than the ASI-negative patients (N = 87; p = 0.009); no differences were noted in the frequency of CSF, electroencephalography, and/or magnetic resonance imaging alterations. Discussion: A subgroup of seropositive patients showed intrathecal synthesis of anti-TPO and, more rarely, of anti-TG antibodies, which might be an indication of central autoimmunity in a subgroup of patients with unipolar depression. The confirmation of elevated ASIs as a biomarker for Hashimoto encephalopathy must await further studies. The relevance of the findings is limited by the study’s retrospective and uncontrolled design.
Efficacy of Corticosteroids in Patients with SARS, MERS and COVID-19: A Systematic Review and Meta-Analysis
Authors: Lee Keum Hwa , Yoon Sojung , Jeong Gwang Hun , Kim Jong Yeob , Han Young Joo , Hong Sung Hwi , Ryu Seohyun , Kim Jae Seok , Lee Jun Young , Yang Jae Won , Lee Jinhee , Solmi Marco , Koyanagi Ai , Dragioti Elena , Jacob Louis , Radua Joaquim , Smith Lee , Oh Hans , Tizaoui Kalthoum , Cargnin Sarah , Terrazzino Salvatore , Ghayda Ramy Abou , Kronbichler Andreas , Shin Jae Il
Published: July 2020

(1) Background: The use of corticosteroids in critical coronavirus infections, including severe acute respiratory syndrome (SARS), Middle East Respiratory Syndrome (MERS), or Coronavirus disease 2019 (COVID-19), has been controversial. However, a meta-analysis on the efficacy of steroids in treating these coronavirus infections is lacking. (2) Purpose: We assessed a methodological criticism on the quality of previous published meta-analyses and the risk of misleading conclusions with important therapeutic consequences. We also examined the evidence of the efficacy of corticosteroids in reducing mortality in SARS, MERS and COVID-19. (3) Methods: PubMed, MEDLINE, Embase, and Web of Science were used to identify studies published until 25 April 2020, that reported associations between steroid use and mortality in treating SARS/MERS/COVID-19. Two investigators screened and extracted data independently. Searches were restricted to studies on humans, and articles that did not report the exact number of patients in each group or data on mortality were excluded. We calculated odds ratios (ORs) or hazard ratios (HRs) under the fixed- and random-effect model. (4) Results: Eight articles (4051 patients) were eligible for inclusion. Among these selected studies, 3416 patients were diagnosed with SARS, 360 patients with MERS, and 275 with COVID-19; 60.3% patients were administered steroids. The meta-analyses including all studies showed no differences overall in terms of mortality (OR 1.152, 95% CI 0.631–2.101 in the random effects model, p = 0.645). However, this conclusion might be biased, because, in some studies, the patients in the steroid group had more severe symptoms than those in the control group. In contrast, when the meta-analysis was performed restricting only to studies that used appropriate adjustment (e.g., time, disease severity), there was a significant difference between the two groups (HR 0.378, 95% CI 0.221–0.646 in the random effects model, p < 0.0001). Although there was no difference in mortality when steroids were used in severe cases, there was a difference among the group with more underlying diseases (OR 3.133, 95% CI 1.670–5.877, p < 0.001). (5) Conclusions: To our knowledge, this study is the first comprehensive systematic review and meta-analysis providing the most accurate evidence on the effect of steroids in coronavirus infections. If not contraindicated, and in the absence of side effects, the use of steroids should be considered in coronavirus infection including COVID-19.
Hyperreflective Material in Optical Coherence Tomography Images of Eyes with Myopic Choroidal Neovascularization May Affect the Visual Outcome
Authors: Mushiga Yasuaki , Minami Sakiko , Uchida Atsuro , Nagai Norihiro , Suzuki Misa , Kurihara Toshihide , Sonobe Hideki , Ban Norimitsu , Watanabe Kazuhiro , Shinoda Hajime , Tsubota Kazuo , Ozawa Yoko
Published: July 2020

The visual outcome of myopic choroidal neovascularization (CNV) after anti-vascular endothelial growth factor (anti-VEGF) therapy varies among individuals. We retrospectively analyzed the data of 24 eyes (24 patients) with treatment-naïve myopic CNV who underwent anti-VEGF monotherapy following a pro-re-nata regimen at the Division of Medical Retina Clinic, Department of Ophthalmology, Keio University Hospital between May 2014 and December 2017. The mean age was 70.6 ± 2.1 years, and 16 (66.7%) patients were female. Overall, the mean best-corrected visual acuity (BCVA) improved (p = 0.034), and the mean height of the hyperreflective material (HRM), involving the CNV lesion recorded by optical coherence tomography, decreased (p < 0.01) 12 months after the initial treatment. Fifteen eyes (62.5%) achieved a BCVA of better than 0.10 in LogMAR at 12 months; they had a better BCVA (p = 0.015) and lower HRM intensity (p = 0.033) at baseline than the others. Remarkably, the BCVA improved (p < 0.05) and the HRM height (p < 0.01) decreased only in eyes with a final BCVA better than 0.10 as early as 1 month after the initial treatment, which was still present at 12 months. The HRM height and intensity, not only the BCVA, would be valuable in evaluating the prognosis of myopic CNV after anti-VEGF therapy, although further study is required.
The Treatment of Cognitive, Behavioural and Motor Impairments from Brain Injury and Neurodegenerative Diseases through Cannabinoid System Modulation—Evidence from In Vivo Studies
Authors: Calina Daniela , Buga Ana Maria , Mitroi Mihaela , Buha Aleksandra , Caruntu Constantin , Scheau Cristian , Bouyahya Abdelhakim , El Omari Nasreddine , El Menyiy Naoual , Docea Anca Oana
Published: July 2020

Neurological disorders such as neurodegenerative diseases or traumatic brain injury are associated with cognitive, motor and behavioural changes that influence the quality of life of the patients. Although different therapeutic strategies have been developed and tried until now to decrease the neurological decline, no treatment has been found to cure these pathologies. In the last decades, the implication of the endocannabinoid system in the neurological function has been extensively studied, and the cannabinoids have been tried as a new promising potential treatment. In this study, we aimed to overview the recent available literature regarding in vivo potential of natural and synthetic cannabinoids with underlying mechanisms of action for protecting against cognitive decline and motor impairments. The results of studies on animal models showed that cannabinoids in traumatic brain injury increase neurobehavioral function, working memory performance, and decrease the neurological deficit and ameliorate motor deficit through down-regulation of pro-inflammatory markers, oedema formation and blood–brain barrier permeability, preventing neuronal cell loss and up-regulating the levels of adherence junction proteins. In neurodegenerative diseases, the cannabinoids showed beneficial effects in decreasing the motor disability and disease progression by a complex mechanism targeting more signalling pathways further than classical receptors of the endocannabinoid system. In light of these results, the use of cannabinoids could be beneficial in traumatic brain injuries and multiple sclerosis treatment, especially in those patients who display resistance to conventional treatment.
Pleural Pressure Pulse in Patients with Pleural Effusion: A New Phenomenon Registered during Thoracentesis with Pleural Manometry
Authors: Grabczak Elzbieta M. , Michnikowski Marcin , Styczynski Grzegorz , Zielinska-Krawczyk Monika , Stecka Anna M. , Korczynski Piotr , Zielinski Krzysztof , Palko Krzysztof J. , Rahman Najib M. , Golczewski Tomasz , Krenke Rafal
Published: July 2020

Pleural manometry enables the assessment of physiological abnormalities of lung mechanics associated with pleural effusion. Applying pleural manometry, we found small pleural pressure curve oscillations resembling the pulse tracing line. The aim of our study was to characterize the oscillations of pleural pressure curve (termed here as the pleural pressure pulse, PPP) and to establish their origin and potential significance. This was an observational cross-sectional study in adult patients with pleural effusion who underwent thoracentesis with pleural manometry. The pleural pressure curves recorded prior to and during fluid withdrawal were analyzed. The presence of PPP was assessed in relation to the withdrawn pleural fluid volume, lung expandability, vital and echocardiographic parameters, and pulmonary function testing. A dedicated device was developed to compare the PPP to the pulse rate. Fifty-four patients (32 women) median age 66.5 (IQR 58.5–78.7) years were included. Well visible and poorly visible pressure waves were detected in 48% and 35% of the patients, respectively. The frequency of PPP was fully concordant with the pulse rate and the peaks of the oscillations reflected the period of heart diastole. PPP was more visible in patients with a slower respiratory rate (p = 0.008), a larger amount of pleural effusion, and was associated with a better heart systolic function assessed by echocardiography (p < 0.05). This study describes a PPP, a new pleural phenomenon related to the cyclic changes in the heart chambers volume. Although the importance of PPP remains largely unknown, we hypothesize that it could be related to lung atelectasis or lower lung and visceral pleura compliance.
Editorial for Special Issue “Radar Technology for Coastal Areas and Open Sea Monitoring”
Authors: Ludeno Giovanni , Uttieri Marco
Published: July 2020

The sea has always played a fundamental role in the social and economic development, as well as in the shaping and functioning of natural ecosystems and services [...]
Hydrodynamic Analysis of Horizontal Axis Tidal Current Turbine under the Wave-Current Condition
Authors: Wang Shu-qi , Zhang Ying , Xie Yang-yang , Xu Gang , Liu Kun , Zheng Yuan
Published: July 2020

To take advantage of the high tidal current velocity near the free surface, the horizontal axis turbine is installed, which inevitably causes hydrodynamic characteristics to effect the turbine by the waves. In this article, we established a numerical calculation method for the hydrodynamic load of a horizontal axis turbine under wave-current conditions. Based on the numerical calculation results, the hydrodynamic loads were decomposed and the influence rules of wave parameters and blade tip immersion depth on the hydrodynamic load were obtained. The study found the following: (1) the multi-frequency fluctuations based on the rotation frequency and incident wave frequency occurred in instantaneous values of the axial load coefficients and energy utilization ratios, and the fluctuation amplitude decreased with the increase of the blade tip immersion depth; (2) the fluctuation amplitude, according to rotation frequency, changed less with the increase of wave period and wave height, and was smaller according to wave frequency; (3) the fluctuation amplitude based on wave frequency increased linearly with the increase of wave height and wave period. The research results can provide the basis and reference for the design and engineering application of tidal current power station.
Towards Coral Reef Resilience
Authors: Chou Loke-Ming , Huang Danwei
Published: July 2020

Coral reef habitats provide valuable ecosystem services which have benefitted human society for millennia, but intense anthropogenic pressure, especially in the latter part of the last century, has resulted in widespread habitat degradation and loss of ecosystem services with severe environmental and societal consequences [...]
Advances in Fungal Peptide Vaccines
Authors: B. R. Da Silva Leandro , P. Taborda Carlos , D. Nosanchuk Joshua
Published: July 2020

Vaccination is one of the greatest public health achievements in the past century, protecting and improving the quality of life of the population worldwide. However, a safe and effective vaccine for therapeutic or prophylactic treatment of fungal infections is not yet available. The lack of a vaccine for fungi is a problem of increasing importance as the incidence of diverse species, including Paracoccidioides, Aspergillus, Candida, Sporothrix, and Coccidioides, has increased in recent decades and new drug-resistant pathogenic fungi are emerging. In fact, our antifungal armamentarium too frequently fails to effectively control or cure mycoses, leading to high rates of mortality and morbidity. With this in mind, many groups are working towards identifying effective and safe vaccines for fungal pathogens, with a particular focus of generating vaccines that will work in individuals with compromised immunity who bear the major burden of infections from these microbes. In this review, we detail advances in the development of vaccines for pathogenic fungi, and highlight new methodologies using immunoproteomic techniques and bioinformatic tools that have led to new vaccine formulations, like peptide-based vaccines.
Corporate Governance and Dividend Policy in the Presence of Controlling Shareholders
Authors: Rodrigues Ricardo , Felício J. Augusto , Matos Pedro Verga
Published: July 2020

Based on agency theory, we focused on the influence of corporate governance in the dividend policy of large listed firms with headquarters in continental Europe countries. Previous research focused on the influence of corporate governance on the performance and risk of listed firms, but the influence of corporate governance on the dividend policy has rarely been addressed despite the importance of dividends for shareholders and the implications on the free cash-flow, whose application may be a source of conflicts between managers and shareholders. In this paper, we study the influence of a set of governance mechanisms on the dividend policy over 12 years (2002 to 2013). The results, based on a panel data analysis, support the importance of governance mechanisms toward the protection of shareholders’ interests, and reveal that the decisions on whether to pay dividends and how much to pay are grounded on different antecedents.
A Review of Driving Factors, Scenarios, and Topics in Urban Land Change Models
Authors: Kim Youjung , Newman Galen , Güneralp Burak
Published: July 2020

Due to the increase in future uncertainty caused by rapid environmental, societal, and technological change, exploring multiple scenarios has become increasingly important in urban planning. Land Change Modeling (LCM) enables planners to have the ability to mold uncertain future land changes into more determined conditions via scenarios. This paper reviews the literature on urban LCM and identifies driving factors, scenario themes/types, and topics. The results show that: (1) in total, 113 driving factors have been used in previous LCM studies including natural, built environment, and socio-economic factors, and this number ranges from three to twenty-one variables per model; (2) typical scenario themes include “environmental protection” and “compact development”; and (3) LCM topics are primarily growth prediction and prediction tools, and the rest are growth-related impact studies. The nature and number of driving factors vary across models and sites, and drivers are heavily determined by both urban context and theoretical framework.
Recent Trends and Developments in Graphene/Conducting Polymer Nanocomposites Chemiresistive Sensors
Authors: Zamiri Golnoush , Haseeb A. S. M. A.
Published: July 2020

The use of graphene and its derivatives with excellent characteristics such as good electrical and mechanical properties and large specific surface area has gained the attention of researchers. Recently, novel nanocomposite materials based on graphene and conducting polymers including polyaniline (PANi), polypyrrole (PPy), poly (3,4 ethyldioxythiophene) (PEDOT), polythiophene (PTh), and their derivatives have been widely used as active materials in gas sensing due to their unique electrical conductivity, redox property, and good operation at room temperature. Mixing these two materials exhibited better sensing performance compared to pure graphene and conductive polymers. This may be attributed to the large specific surface area of the nanocomposites, and also the synergistic effect between graphene and conducting polymers. A variety of graphene and conducting polymer nanocomposite preparation methods such as in situ polymerization, electropolymerization, solution mixing, self-assembly approach, etc. have been reported and utilization of these nanocomposites as sensing materials has been proven effective in improving the performance of gas sensors. Review of the recent research efforts and developments in the fabrication and application of graphene and conducting polymer nanocomposites for gas sensing is the aim of this review paper.
Analysis of the Nanoparticle Dispersion and Its Effect on the Crystalline Microstructure in Carbon-Additivated PA12 Feedstock Material for Laser Powder Bed Fusion
Authors: Hupfeld Tim , Sommereyns Alexander , Riahi Farbod , Doñate-Buendía Carlos , Gann Stan , Schmidt Michael , Gökce Bilal , Barcikowski Stephan
Published: July 2020

Driven by the rapid development of additive manufacturing technologies and the trend towards mass customization, the development of new feedstock materials has become a key aspect. Additivation of the feedstock with nanoparticles is a possible route for tailoring the feedstock material to the printing process and to modify the properties of the printed parts. This study demonstrates the colloidal additivation of PA12 powder with laser-synthesized carbon nanoparticles at >95% yield, focusing on the dispersion of the nanoparticles on the polymer microparticle surface at nanoparticle loadings below 0.05 vol%. In addition to the descriptors “wt%” and “vol%”, the descriptor “surf%” is discussed for characterizing the quantity and quality of nanoparticle loading based on scanning electron microscopy. The functionalized powders are further characterized by confocal dark field scattering, differential scanning calorimetry, powder rheology measurements (avalanche angle and Hausner ratio), and regarding their processability in laser powder bed fusion (PBF-LB). We find that heterogeneous nucleation is induced even at a nanoparticle loading of just 0.005 vol%. Finally, analysis of the effect of low nanoparticle loadings on the final parts’ microstructure by polarization microscopy shows a nanoparticle loading-dependent change of the dimensions of the lamellar microstructures within the printed part.
Catastrophic Influence of Global Distortional Modes on the Post-Buckling Behavior of Opened Columns
Authors: Teter Andrzej , Kolakowski Zbigniew
Published: July 2020

The multimodal buckling of thin-walled isotropic columns with open cross-sections under uniform compression is discussed. Column lengths were selected to enable strong interactions between selected eigenmodes. In the case of short columns or very long ones subjected to compression, single-mode buckling can be observed only and the effect under discussion does not occur. In the present study, the influence of higher global modes on the load-carrying capacity and behavior in the post-buckling state of thin-walled structures with open cross-sections is analyzed in detail. In the literature known to the authors, higher global modes are always neglected practically in the analysis due to their very high values of bifurcation loads. However, the phenomenon of an unexpected loss in the load-carrying capacity of opened columns can be observed in the experimental investigations. It might be explained using multimode buckling when the higher global distortional-flexural buckling modes are taken into account. In the conducted numerical simulations, a significant influence of higher global distortional-flexural buckling modes on the post-buckling equilibrium path of uniformly compressed columns with C- and TH-shaped (the so-called “top-hat”) cross-sections was observed. The columns of two lengths, for which strong interactions between selected eigenmodes were seen, were subject to consideration. Two numerical methods were applied, namely, the semi-analytical method (SAM) using Koiter’s perturbation approach and the finite element method (FEM), to solve the problem. The SAM results showed that the third mode had a considerable impact on the load-carrying capacity, whereas the FEM results confirmed a catastrophic effect of the modes on the behavior of the structures under analysis, which led to a lack of convergence of numerical calculations despite an application of the Riks algorithm. All elastic-plastic effects were neglected.
A Two-Year Evaluation of Corrosion-Induced Damage to Hot Galvanized Reinforcing Steel B500SP in Chloride Contaminated Concrete
Authors: Jaśniok Mariusz , Sozańska Maria , Kołodziej Jacek , Chmiela Bartosz
Published: July 2020

Corrosion-induced damage to concrete reinforced with bars is a serious problem regarding technical and economic aspects and strongly depends on used materials, corrosion environment, and service life. Tests described in this paper refer to a two-year evaluation of the effectiveness of protection provided by zinc-coated low-carbon reinforcing steel of grade B500SP in concrete against chloride corrosion. Performed tests were comparative and included measurements conducted on four groups of concrete test elements with dimensions of 40 mm × 40 mm × 140 mm reinforced with a bar having a diameter of ϕ8 mm. Particular groups were a combination of different types of concrete with or without chloride additives, with galvanized or black steel. Chlorides as CaCl2 were added to the concrete mix in the amount of 3% of cement weight in concrete. Reinforced concrete specimens were periodically monitored within two years using the following techniques: linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). Polarization measurements were conducted in a three-electrode arrangement, in which a rebar in concrete served as a working electrode, stainless steel sheet was used as an auxiliary electrode, and Cl−/AgCl,Ag was a reference electrode. Comparative tests of changes in the density of corrosion current in concrete specimens without chloride additives basically demonstrated no development of corrosion, and possible passivation was expected in case of black steel. Higher densities of corrosion current were observed for galvanized steel during first days of testing. The reason was the dissolution of zinc after the contact with initially high pH of concrete pore solution. Six-month measurements demonstrated a higher density of corrosion current in concrete specimens with high concentration of chlorides, which unambiguously indicated corrosion in concrete reinforced with galvanized or black steel. Densities of corrosion current determined for selected specimens dramatically decreased after an 18-month interval in measurements. Corrosion was even inhibited on black steel as an insulating barrier of corrosion products was formed. The above observations were confirmed with structural studies using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. Results obtained from corrosion (LPR, EIS) and structural (SEM, EDS) tests on specimens of concrete reinforced with steel B500SP demonstrated a very favorable impact of zinc coating on steel by providing two-year protection against corrosion in the environment with very high chloride content.
Mathematical Model Describing the Influence of Geometrical Parameters of Multichannel Dies on the Limit Force of Dry Ice Extrusion Process
Authors: Górecki Jan , Talaśka Krzysztof , Wałęsa Krzysztof , Wilczyński Dominik , Wojtkowiak Dominik
Published: July 2020

The article presents a formulated mathematical model that enables the determination of the required compressive force in the extrusion process of dry ice employing multichannel dies. This is the main parameter in the piston-based dry ice extrusion process. The indicated model was developed for the purpose of further improvement of the energy efficiency of this extrusion process. It allows for the determination of the value of compressive force by accounting for 12 variables related to the geometrical parameters of the die and the physical characteristics of dry ice. Furthermore, the paper also provides descriptions of the empirical study methodologies together with the results. These were carried out in order to determine the difference between the results of mathematical modeling and actual measurement results. The final part of the article presents the results of the analysis of the mathematical model’s sensitivity to the change of the physical characteristics of dry ice. The formulated tool may be employed to adapt the geometric parameters of the die in order to obtain the desired compressive force value and dry ice granulation with reduced energy consumption.
Characterization of Microcrack Orientation Using the Directivity of Secondary Sound Source Induced by an Incident Ultrasonic Transverse Wave
Authors: Wang Jishuo , Xu Caibin , Zhao Youxuan , Hu Ning , Deng Mingxi
Published: July 2020

In this paper, characterization of the orientation of a microcrack is quantitatively investigated using the directivity of second harmonic radiated by the secondary sound source (SSS) induced by the nonlinear interaction between an incident ultrasonic transverse wave (UTW) and a microcrack. To this end, a two-dimensional finite element (FE) model is established based on the bilinear stress–strain constitutive relation. Under the modulation of contact acoustic nonlinearity (CAN) to the incident UTW impinging on the microcrack examined, the microcrack itself is treated as a SSS radiating the second harmonic. Thus, the directivity of the second harmonic radiated by the SSS is inherently related to the microcrack itself, including its orientation. Furthermore, the effects of the stiffness difference between the compressive and tensile phases in the bilinear stress–strain model, and the UTW driving frequency, as well as the radius of the sensing circle on the SSS directivity are discussed. The FE results show that the directivity pattern of the second harmonic radiated by the SSS is closely associated with the microcrack orientation, through which the microcrack orientation can be characterized without requiring a baseline signal. It is also found that the SSS directivity varies sensitively with the driving frequency of the incident UTW, while it is insensitive to the stiffness difference between the compressive and tensile phases in the bilinear stress–strain model and the radius of the sensing circle. The results obtained here demonstrate that the orientation of a microcrack can be characterized using the directivity of the SSS induced by the interaction between the incident UTW and the microcrack.
Additive Manufacturing of Isotropic NdFeB PPS Bonded Permanent Magnets
Authors: Paranthaman M. Parans , Yildirim Volkan , Lamichhane Tej Nath , Begley Benjamin A. , Post Brian K. , Hassen Ahmed A. , Sales Brian C. , Gandha Kinjal , Nlebedim Ikenna C.
Published: July 2020

Extrusion based additive manufacturing of polymer composite magnets can increase the solid loading volume fraction with greater mechanical force through the printing nozzle as compared to traditional injection molding process. About 63 vol% of isotropic NdFeB magnet powders were compounded with 37 vol% of polyphenylene sulfide and bonded permanent magnets were fabricated while using Big Area Additive Manufacturing without any degradation in magnetic properties. The polyphenylene sulfide bonded magnets have a tensile stress of 20 MPa, almost double than that of nylon bonded permanent magnets. Additively manufactured and surface-protective-resin coated bonded magnets meet the industrial stability criterion of up to 175 °C with a flux-loss of 2.35% over 1000 h. They also exhibit better corrosion resistance behavior when exposed to acidic (pH = 1.35) solution for 24 h and also annealed at 80 °C over 100 h (at 95% relative humidity) over without coated magnets. Thus, polyphenylene sulfide bonded, additively manufactured, protective resin coated bonded permanent magnets provide better thermal, mechanical, and magnetic properties.
Extended Polysaccharide Analysis within the Liposomal Encapsulation of Polysaccharides System
Authors: Nayerhoda Roozbeh , Park Dongwon , Jones Charles , Bou Ghanem Elsa N. , Pfeifer Blaine A.
Published: July 2020

The Liposomal Encapsulation of Polysaccharides (LEPS) dual antigen vaccine carrier system was assessed across two distinct polysaccharides for encapsulation efficiency, subsequent liposomal surface adornment with protein, adjuvant addition, and size and charge metrics. The polysaccharides derive from two different serotypes of Streptococcus pneumoniae and have traditionally served as the active ingredients of vaccines against pneumococcal disease. The LEPS system was designed to mimic glycoconjugate vaccines that covalently couple polysaccharides to protein carriers; however, the LEPS system uses a noncovalent co-localization mechanism through protein liposomal surface attachment. In an effort to more thoroughly characterize the LEPS system across individual vaccine components and thus support broader future utility, polysaccharides from S. pneumoniae serotypes 3 and 4 were systematically compared within the LEPS framework both pre- and post-surface protein attachment. For both polysaccharides, ≥85% encapsulation efficiency was achieved prior to protein surface attachment. Upon protein attachment with either a model protein (GFP) or a pneumococcal disease antigen (PncO), polysaccharide encapsulation was maintained at ≥61% encapsulation efficiency. Final LEPS carriers were also evaluated with and without alum as an included adjuvant, with encapsulation efficiency maintained at ≥30%, while protein surface attachment efficiency was maintained at ≥~50%. Finally, similar trends and distributions were observed across the different polysaccharides when assessed for liposomal zeta potential and size.
Demonstration of a SiC Protective Coating for Titanium Implants
Authors: Fares Chaker , Hsu Shu-Min , Xian Minghan , Xia Xinyi , Ren Fan , Mecholsky John J. , Gonzaga Luiz , Esquivel-Upshaw Josephine
Published: July 2020

To mitigate the corrosion of titanium implants and improve implant longevity, we investigated the capability to coat titanium implants with SiC and determined if the coating could remain intact after simulated implant placement. Titanium disks and titanium implants were coated with SiC using plasma-enhanced chemical vapor deposition (PECVD) and were examined for interface quality, chemical composition, and coating robustness. SiC-coated titanium implants were torqued into a Poly(methyl methacrylate) (PMMA) block to simulate clinical implant placement followed by energy dispersive spectroscopy to determine if the coating remained intact. After torquing, the atomic concentration of the detectable elements (silicon, carbon, oxygen, titanium, and aluminum) remained relatively unchanged, with the variation staying within the detection limits of the Energy Dispersive Spectroscopy (EDS) tool. In conclusion, plasma-enhanced chemical vapor deposited SiC was shown to conformably coat titanium implant surfaces and remain intact after torquing the coated implants into a material with a similar hardness to human bone mass.
The Effects of Cyclic Loading and Motion on the Implant–Cement Interface and Cement Mantle of PEEK and Cobalt–Chromium Femoral Total Knee Arthroplasty Implants: A Preliminary Study
Authors: de Ruiter Lennert , Cowie Raelene M. , Jennings Louise M. , Briscoe Adam , Janssen Dennis , Verdonschot Nico
Published: July 2020

This study investigated the fixation of a cemented PEEK femoral TKA component. PEEK and CoCr implants were subjected to a walking gait cycle for 10 million cycles (MC), 100,000 cycles or 0 cycles (unloaded control). A method was developed to assess the fixation at the cement–implant interface, which exposed the implants to a fluorescent penetrant dye solution. The lateral condyles of the implants were then sectioned and viewed under fluorescence to investigate bonding at the cement–implant interface and cracking of the cement mantle. When tested for 100,000 cycles, debonding of the cement–implant interface occurred in both PEEK (61%) and CoCr (13%) implants. When the duration of testing was extended (10 MC), the percentage debonding was further increased for both materials to 88% and 61% for PEEK and CoCr, respectively. The unloaded PEEK specimens were 79% debonded, which suggests that, when PEEK femoral components are cemented, complete bonding may never occur. Analysis of cracks in the cement mantle showed an absence of full-thickness cracks in the unloaded control group. For the 100,000-cycle samples, on average, 1.3 and 0.7 cracks were observed for PEEK and CoCr specimens, respectively. After 10 MC, these increased to 24 for PEEK and 19 for CoCr. This was a preliminary study with a limited number of samples investigated, but shows that, after 10 MC under a walking gait, substantial debonding was visible for both PEEK and CoCr implants at the cement–implant interface and no significant difference in the number of cement cracks was found between the two materials.
Investigation of Strength and Fatigue Life of Rubber Asphalt Mixture
Authors: Yuan Jiang , Lv Songtao , Peng Xinghai , You Lingyun , Borges Cabrera Milkos
Published: July 2020

Strength and fatigue life are essential parameters of pavement structure design. To accurately determine the pavement structure resistance of rubber asphalt mixture, the strength tests at various temperatures, loading rate, and fatigue tests at different stress levels were conducted in this research. Based on the proposed experiments, the change law of rubber asphalt mixture strength with different temperatures and loading rates was revealed. The phenomenological fatigue equation of rubber asphalt mixture was established. The genetic algorithm optimized backpropagation neural network (GA-BPNN) is highly reliable for optimizing production processes in civil engineering, and it has a remarkable application effect. A GA-BPNN strength and fatigue life prediction model was created in this study. The reliability of the prediction model was verified through experiments. The results showed that the rubber asphalt mixture strength decreases and increases with the increase of temperature and loading rate, respectively. The goodness of fit of the rubber asphalt mixture strength and fatigue life prediction model based on the GA-BPNN could reach 0.989 and 0.998, respectively. The indicators of the fatigue life prediction model are superior to the conventional phenomenological fatigue equation model. The GA-BPNN provides an effective method for predicting the rubber asphalt mixture strength and fatigue life, which significantly improves the accuracy of the resistance design of the rubber asphalt pavement structure.
Case Study of the Tensile Fracture Investigation of Additive Manufactured Austenitic Stainless Steels Treated at Cryogenic Conditions
Authors: Bidulský Róbert , Bidulská Jana , Gobber Federico Simone , Kvačkaj Tibor , Petroušek Patrik , Actis-Grande Marco , Weiss Klaus-Peter , Manfredi Diego
Published: July 2020

Additive manufacturing is a key enabling technology in the manufacture of highly complex shapes, having very few geometric limitations compared to traditional manufacturing processes. The present paper aims at investigating mechanical properties at cryogenic temperatures for a 316L austenitic stainless steel, due to the wide possible cryogenic applications such as liquid gas confinement or superconductors. The starting powders have been processed by laser powder bed fusion (LPBF) and tested in the as-built conditions and after stress relieving treatments. Mechanical properties at 298, 77 and 4.2 K from tensile testing are presented together with fracture surfaces investigated by field emission scanning electron microscopy. The results show that high tensile strength at cryogenic temperature is characteristic for all samples, with ultimate tensile strength as high as 1246 MPa at 4.2 K and 55% maximum total elongation at 77 K. This study can constitute a solid basis for investigating 316L components by LPBF for specific applications in cryogenic conditions.
Effect of Placement Technology on the Bond Strength Between Two Layers of Self-Compacting Concrete
Authors: Dybeł Piotr , Kucharska Milena
Published: July 2020

Self-compacting concrete (SCC) should generally be placed continuously, but it is not uncommon for contractors to be forced to use interruptions in concrete works due to delivery delays. The multilayer casting of SCC can cause weak bond conditions in the contact area of subsequent layers. Methods of preventing cold joint or lift line formation for normal concretes are not suitable for self-compacting concretes. This article provides research on the effect of multilayer casting technology on the bond strength between two layers of SCC. Three technological variants of connecting successive layers of SCC mixture on beam elements were analyzed: The free flow of the mixture, dropping the mixture from a greater height, and mechanical disturbance of the first layer. Three delay times were applied: 30, 45, and 60 min between two layers of SCC. In general, the research revealed that, regardless of the multilayer casting variant, the bond strength between two layers decreased as the delay time was extended. The best performance and the lowest drop in bond strength were obtained for samples with a mechanically disturbed first layer, independent of the delay time. This method gave similar results to a reference element made without a break in concreting. It was also demonstrated that current recommendations and standard guidelines for multilayer casting appear to be insufficient for ensuring an adequate bond between layers.
Flexibility of Biodegradable Polymer Stents with Different Strut Geometries
Authors: Chen Chong , Xiong Yan , Li Zhongyou , Chen Yu
Published: July 2020

Objective: Biodegradable stents (BDSs) represent a new technological development in the field of cardiovascular angioplasty; good flexibility helps stents pass through tortuous vessels during delivery and reduces the amount of damage caused to blood vessels. This study investigates the relationship between flexibility and the geometry of BDS struts. Methods: Four stent struts with different geometry (circular, triangular, hexagonal, and spline curved) and the same links were modeled to evaluate their flexibility via a three-point bending experimental method and a numerical method. Results: The bending state of the four stents was well-balanced. The bending effect of the four stents was different. Under the same conditions, the circular and spline curved stents showed the best bending effects while the hexagonal stent was the worst. However, these differences were not significant. Conclusion: The flexibility of BDSs is related to the geometry of the struts and links; however, the geometry of the struts has less effect on flexibility than the links. The greater the area enclosed by the strut centerline, the better flexibility of the stent.
Pseudo-Ductility, Morphology and Fractography Resulting from the Synergistic Effect of CaCO3 and Bentonite in HDPE Polymer Nano Composite
Authors: Ahmed Tauseef , Ya Hamdan H. , Khan Rehan , Hidayat Syah Lubis Abdul Munir , Mahadzir Shuhaimi
Published: July 2020

Polymeric materials such as High density polyethylene(HDPE) are ductile in nature, having very low strength. In order to improve strength by non-treated rigid fillers, polymeric materials become extremely brittle. Therefore, this work focuses on achieving pseudo-ductility (high strength and ductility) by using a combination of rigid filler particles (CaCO3 and bentonite) instead of a single non-treated rigid filler particle. The results of all tensile-tested (D638 type i) samples signify that the microstructural features and surface properties of rigid nano fillers can render the required pseudo-ductility. The maximum value of tensile strength achieved is 120% of the virgin HDPE, and the value of elongation is retained by 100%. Furthermore, the morphological and fractographic analysis revealed that surfactants are not always going to obtain polymer–filler bonding, but the synergistic effect of filler particles can carry out sufficient bonding for stress transfer. Moreover, pseudo-ductility was achieved by a combination of rigid fillers (bentonite and CaCO3) when the content of bentonite dominated as compared to CaCO3. Thus, the achievement of pseudo-ductility by the synergistic effect of rigid particles is the significance of this study. Secondly, this combination of filler particles acted as an alternative for the application of surfactant and compatibilizer so that adverse effect on mechanical properties can be avoided.
Experimental Investigation of the Blanked Surface of C5191 Phosphor Bronze Sheet over a Wide Range of Blanking Speeds
Authors: Wang Lei , Hu Daochun , Chen Minghe , Wang Hongjun
Published: July 2020

The influence of blanking speed on the blanked surface quality of C5191 bronze phosphorus sheets, with a thickness of 0.12 mm, was systematically studied to demonstrate the mechanism under high speed blanking. The morphology and microstructure of the blanked edge were observed by using a variety of techniques, including optical microscopy (OM), scanning electron microscope (SEM), electron backscatter diffraction (EBSD), and transmission electron microscope (TEM). The results revealed that the local temperature and microhardness of the shear zone increased with the increase in blanking speed. Moreover, the quality of blanked edge significantly improved with the increase in blanking speed due to the combined influence of strain rate hardening and thermal softening. In addition, the blanked edge grains were elongated along the blanking direction and formed dislocation cells and sub-grains in some areas. The blanked edge is dominated by {000} <100> cubic texture at higher blanking speeds, and {112} <111> texture at lower blanking speeds. When punched at an ultra-high speed of 3000 strokes per minute (SPM 3000), the local area of the blanked edge exhibited distinct microstructural features, including low dislocation density, nanocrystals with high-angle grain boundaries, and significant differences in grain orientation. Additionally, the selected area electron diffraction (SAED) pattern exhibited a discontinuous ring-like structure, indicating the occurrence of adiabatic shearing with dynamic recrystallization.
Fluorination of Diamond Nanoparticles in Slow Neutron Reflectors Does Not Destroy Their Crystalline Cores and Clustering While Decreasing Neutron Losses
Authors: Bosak Alexei , Dideikin Artur , Dubois Marc , Ivankov Oleksandr , Lychagin Egor , Muzychka Alexei , Nekhaev Grigory , Nesvizhevsky Valery , Nezvanov Alexander , Schweins Ralf , Strelkov Alexander , Vul’ Alexander , Zhernenkov Kirill
Published: July 2020

If the wavelength of radiation and the size of inhomogeneities in the medium are approximately equal, the radiation might be intensively scattered in the medium and reflected from its surface. Such efficient nanomaterial reflectors are of great scientific and technological interest. In previous works, we demonstrated a significant improvement in the efficiency of reflection of slow neutrons from a powder of diamond nanoparticles by replacing hydrogen located on the surface of nanoparticles with fluorine and removing the residual sp2 amorphous shells of nanoparticles via the fluorination process. In this paper, we study the mechanism of this improvement using a set of complementary experimental techniques. To analyze the data on a small-angle scattering of neutrons and X-rays in powders of diamond nanoparticles, we have developed a model of discrete-size diamond nanospheres. Our results show that fluorination does not destroy either the crystalline cores of nanoparticles or their clustering in the scale range of 0.6–200 nm. This observation implies that it does not significantly affect the neutron scattering properties of the powder. We conclude that the overall increase in reflectivity from the fluorinated nanodiamond powder is primarily due to the large reduction of neutron losses in the powder caused by the removal of hydrogen contaminations.