bluuebunny/crossref_metadata_2025 huggingface dataset:
Female Pelvic Floor Dysfunction Continues to Negatively Impact Quality-of-Life during the COVID-19 Lockdown
Authors: Carlin Greta Lisa , Kimberger Oliver , Morgenbesser Raffaela , Umek Wolfgang , Kölbl Heinz , Bodner Klaus , Bodner-Adler Barbara
Published: March 2021

The COVID-19 pandemic led to dramatical changes in elective medical care. We analysed its impact on patients with female pelvic floor dysfunction during the 6 weeks of lockdown in Austria. A cross-sectional study was conducted: All 99 women who presented at the urogynaecologic outpatient clinic of the Medical University of Vienna with pelvic organ prolapse (POP) or urinary incontinence (UI) from December 2019 up to the lockdown in March 2020 were included and contacted. 97% of these women (96 participants) agreed to participate in the survey conducted to asses pelvic floor related quality of life (QoL) through telephone- interrogation. The mean age was 59 ± 14.8 years, the POP group consisted of 42 women while the UI group included 54 women. Most participants (83% of POP and 81% of UI cases) stated that their female pelvic floor dysfunction had remained equally relevant or had become even more significant during the lockdown. Associated symptoms and psychological strain also maintained their relevance during the lockdown (UI: p = 0.229; POP: p = 0.234). Furthermore, 97% of all interviewed women indicated to be strongly willing to continue their treatment. A generalised linear model regression revealed no clinical or demographic risk factors for psychological strain during the lockdown (p > 0.05). Our results demonstrate that women’s QoL remains significantly impaired by their pelvic-floor disorders even during a worldwide crisis such as COVID-19. Therefore, elective disciplines such as urogynaecology urgently require novel and innovative strategies for continued patient care even in times of a lockdown.
Fragility Fractures and Imminent Fracture Risk in the Spanish Population: A Retrospective Observational Cohort Study
Authors: Montoya-García Maria-José , Giner Mercè , Marcos Rodrigo , García-Romero David , Olmo-Montes Francisco-Jesús , Miranda Mª José , Hernández-Cruz Blanca , Colmenero Miguel-Angel , Vázquez-Gámez Mª Angeles
Published: March 2021

Fragility fractures constitute a major public health problem worldwide, causing important high morbidity and mortality rates. The aim was to present the epidemiology of fragility fractures and to assess the imminent risk of a subsequent fracture and mortality. This is a retrospective population-based cohort study (n = 1369) with a fragility fracture. We estimated the incidence rate of index fragility fractures and obtained information on the subsequent fractures and death during a follow-up of up to three years. We assessed the effect of age, sex, and skeletal site of index fracture as independent risk factors of further fractures and mortality. Incidence rate of index fragility fractures was 86.9/10,000 person-years, with highest rates for hip fractures in women aged ≥80 years. The risk of fracture was higher in subjects with a recent fracture (Relative Risk(RR), 1.80; p < 0.01). Higher age was an independent risk factor for further fracture events. Significant excess mortality was found in subjects aged ≥80 years and with a previous hip fracture (hazard ratio, 3.43 and 2.48, respectively). It is the first study in Spain to evaluate the incidence of major osteoporotic fractures, not only of the hip, and the rate of imminent fracture. Our results provide further evidence highlighting the need for early treatment.
HIV and Sexual Dysfunction in Men
Authors: De Vincentis Sara , Tartaro Giulia , Rochira Vincenzo , Santi Daniele
Published: March 2021

Sexual issues tend to go unaddressed in human immunodeficiency virus (HIV) management, although overt sexual dysfunctions are more prevalent in people living with HIV than uninfected people. Erectile dysfunction is the most frequent sexual problem, with a prevalence of 30–50% even in men <40 years of age, but other issues such as loss of libido and ejaculatory disorders should not be overlooked. Peculiar factors related to HIV infection (e.g., fear of virus transmission, changes in body image, HIV-related comorbidities, HIV distress and stigma), alongside classical factors non-related to HIV, should be considered when approaching sexual problems in HIV patients. For this reason, the diagnostic and therapeutic workout of sexual dysfunction in the context of HIV requires a multidisciplinary approach, involving specialists in both infectious diseases and sexual medicine. This narrative review presents an overview of current knowledge on sexual dysfunction in HIV men, deepening the factors driving and taking part in these issues, providing advice for the clinical approach, and underlining the importance of caring for sexual health to improve the quality of life of HIV patients.
Investigating the Relationship between Glaucoma Prevalence and Trabecular Meshwork Length
Authors: Choi Wungrak , Cho Hyuna , Kim Eun Woo , Bae Hyoung Won , Kim Chan Yun , Seong Gong Je
Published: March 2021

Glaucoma is one of the most common causes of blindness worldwide, but the risk factors of glaucoma are yet to be fully understood. We investigated the relationship between the prevalence of glaucoma and trabecular meshwork (TM) length by comparing the mean TM length of a South Korean population with that of another ethnic population. We included 250 eyes of 125 patients who underwent anterior segment optical coherence tomography at Yonsei University Gangnam Severance Hospital between January 2015 and December 2017. We measured the distance from the scleral spur to Schwalbe’s line in patients with open and closed angles and calculated the TM length using the open- and closed-angle ratios in the general population. The mean TM length of the patients in our study was 752 ± 116 μm. Considering the compensated data, the estimated true mean TM length in the Korean population was 793 ± 76 μm, which was similar to the mean TM length of a previously evaluated Hispanic population, but differed significantly from those of previously evaluated Asian (Chinese), Caucasian, and African-American populations (p < 0.05). Our results support the hypothesis that the development of glaucoma would be affected by TM length.
Damage by Improvised Incendiary Devices on Carbon Fiber-Reinforced Polymer Matrix Composites
Authors: Eibl Sebastian
Published: March 2021

This study focuses on short-term thermal degradation of polymer matrix composites by one-sided impact of improvised incendiary devices (IID). Specimens of two commercial composites HexPly® 8552/IM7 and M18-1/G939 with various thicknesses (1–8 mm) are systematically investigated as well as sandwich structures thereof, applying various amounts of fire accelerant predominantly in laboratory scale fire tests. Results of preceding large-scale fire tests with IIDs justify the chosen conditions for the laboratory-scale fire tests. The aim is to correlate the amount of fire accelerant with heat damage and residual mechanical strength. Thermal damage is characterized visually and by ultrasonic testing, infrared spectroscopy, and residual interlaminar shear strength. Matrix degradation and combustion only contribute to the overall amount of released heat by the fire accelerant for thin and especially vertically aligned panels as tested by a cone calorimeter (without electrical heating), but not for horizontally orientated and thicker panels. Degradation processes are discussed in detail. Protective effects are observed for typical coatings, a copper mesh applied for protection against lightning strike, combinations thereof as well as an intumescent coating. Especially sandwich structures are prone to severe damage by assaults with IID, such as Molotov cocktails.
MTMS-Based Aerogel Constructs for Immobilization of Plant Hairy Roots: Effects on Proliferation of Rindera graeca Biomass and Extracellular Secretion of Naphthoquinones
Authors: Nowak Bartosz , Kawka Mateusz , Wierzchowski Kamil , Sykłowska-Baranek Katarzyna , Pilarek Maciej
Published: March 2021

Unique biosynthetic abilities revealed by plants determine in vitro cultures of hairy roots as a suitable source of pharmaceutically relevant bioactive compounds. The basic aim of the study was to examine the applicability of aerogel composed of methyltrimethoxysilane (MTMS) for immobilization of Rindera graeca hairy roots by identifying quantitative effects of biomass proliferation and naphthoquinones extracellular secretion in the aerogel-supported culture system. R. graeca hairy roots were simultaneously cultured for 28-days, as (i) nonimmobilized biomass (reference system), (ii) biomass immobilized on macroporous polyurethane foam (PUF), (iii) biomass with disintegrated MTMS aerogel, (iv) biomass immobilized on polypropylene (PP) fibers (as control), and (v) biomass immobilized on monolithic PP-reinforced MTMS aerogel. MTMS aerogel exhibited high level of biocompatibility toward R. graeca hairy roots which grew into the structure of monolithic aerogel-based constructs. Monolithic MTMS-based constructs significantly promoted the proliferation of hairy roots, resulting in 55% higher fresh mass than the reference system. The highest level of naphthoquinones productivity, i.e., 653 µg gDW−1, was noted for PUF-supported culture system.
Autonomous Underwater Vehicles and Field of View in Underwater Operations
Authors: Ramírez Isaac Segovia , Bernalte Sánchez Pedro José , Papaelias Mayorkinos , Márquez Fausto Pedro García
Published: March 2021

Submarine inspections and surveys require underwater vehicles to operate in deep waters efficiently, safely and reliably. Autonomous Underwater Vehicles employing advanced navigation and control systems present several advantages. Robust control algorithms and novel improvements in positioning and navigation are needed to optimize underwater operations. This paper proposes a new general formulation of this problem together with a basic approach for the management of deep underwater operations. This approach considers the field of view and the operational requirements as a fundamental input in the development of the trajectory in the autonomous guidance system. The constraints and involved variables are also defined, providing more accurate modelling compared with traditional formulations of the positioning system. Different case studies are presented based on commercial underwater cameras/sonars, analysing the influence of the main variables in the measurement process to obtain optimal resolution results. The application of this approach in autonomous underwater operations ensures suitable data acquisition processes according to the payload installed onboard.
Failure Pressure Prediction of a Corroded Pipeline with Longitudinally Interacting Corrosion Defects Subjected to Combined Loadings Using FEM and ANN
Authors: Lo Michael , Karuppanan Saravanan , Ovinis Mark
Published: March 2021

Machine learning tools are increasingly adopted in various industries because of their excellent predictive capability, with high precision and high accuracy. In this work, analytical equations to predict the failure pressure of a corroded pipeline with longitudinally interacting corrosion defects subjected to combined loads of internal pressure and longitudinal compressive stress were derived, based on an artificial neural network (ANN) model trained with data obtained from the finite element method (FEM). The FEM was validated against full-scale burst tests and subsequently used to simulate the failure of a pipeline with various corrosion geometric parameters and loadings. The results from the finite element analysis (FEA) were also compared with the Det Norske Veritas (DNV-RP-F101) method. The ANN model was developed based on the training data from FEA and its performance was evaluated after the model was trained. Analytical equations to predict the failure pressure were derived based on the weights and biases of the trained neural network. The equations have a good correlation value, with an R2 of 0.9921, with the percentage error ranging from −9.39% to 4.63%, when compared with FEA results.
Feasibility Study for the Extraction of Wave Energy along the Coast of Ensenada, Baja California, Mexico
Authors: Hernandez-Sanchez Tzeltzin , Bonasia Rosanna , Scaini Chiara
Published: March 2021

Mexico is one of the countries with the highest emissions of greenhouse gases. In order to reduce the emission of contaminants due to fossil fuels, the state of Baja California has recently launched several research projects for the optimization of facilities for the exploitation of renewable sources, and in particular wave energy. In this work a first-level feasibility study of energy extraction from wave motion is presented for the Ensenada coast, along a complex distance of more than 200 km. The methodology proposed provides good spatial and temporal resolution for wave heights and periods calculation and consequently for the wave power. The methodology is based on the application of the coupled Simulated Waves Nearshore and Advanced Circulation (SWAN + ADCIRC) model for generation, propagation and dissipation of waves. To take into account the meteorological variability within a 21-year dataset, the Typical Meteorological Year method was applied. Results show that overall, the most persistent energy potential during the year is >2 kW/m, with peaks of 5 and 10 kW/m during few months. Given the theoretical energy potential calculated, the Ensenada coast could produce hundreds of GWh per year. The proposed methodology can be applied for the exploration of other coasts with energy potential.
Pharmacogenomic Biomarkers in US FDA-Approved Drug Labels (2000–2020)
Authors: Kim Jeeyun A. , Ceccarelli Rachel , Lu Christine Y.
Published: March 2021

Pharmacogenomics (PGx) is a key subset of precision medicine that relates genomic variation to individual response to pharmacotherapy. We assessed longitudinal trends in US FDA approval of new drugs labeled with PGx information. Drug labels containing PGx information were obtained from Drugs@FDA and guidelines from PharmGKB were used to compare the actionability of PGx information in drug labels across therapeutic areas. The annual proportion of new drug approvals with PGx labeling has increased by nearly threefold from 10.3% (n = 3) in 2000 to 28.2% (n = 11) in 2020. Inclusion of PGx information in drug labels has increased for all clinical areas over the last two decades but most prominently for cancer therapies, which comprise the largest proportion (75.5%) of biomarker–drug pairs for which PGx testing is required. Clinically actionable information was more frequently observed in biomarker–drug pairs associated with cancer drugs compared to those for other therapeutic areas (n = 92 (59.7%) vs. n = 62 (40.3%), p < 0.0051). These results suggest that further evidence is needed to support the clinical adoption of pharmacogenomics in non-cancer therapeutic areas.
Can You Make Better Decisions If You Are Bilingual?
Authors: Kirova Alena , Camacho Jose
Published: March 2021

Studies have shown that “framing bias,” a phenomenon in which two different presentations of the same decision-making problem provoke different answers, is reduced in a foreign language (the Foreign Language effect, FLe). Three explanations have emerged to account for the difference. First, the cognitive enhancement hypothesis states that lower proficiency in the FL leads to more deliberate processing, reducing the framing bias. Second, contradicting the previous, the cognitive overload hypothesis, states that the cognitive load actually induces speakers to make less rational decisions in the FL. Finally, the reduced emotionality hypothesis suggests that speakers have less of an emotional connection to a foreign language (FL), causing an increase in rational language processing. Previous FLe research has involved both FL and non-FL speakers such as highly proficient acculturated bilinguals. Our study extends this research program to a population of heritage speakers of Spanish (HS speakers), whose second language (English) is dominant and who have comparable emotional resonances in both of their languages. We compare emotion-neutral and emotion-laden tasks: if reduced emotionality causes the FLe, it should only be present in emotion-laden tasks, but if it is caused by cognitive load, it should be present across tasks. Ninety-eight HS speakers, with varying degrees of proficiency in Spanish, exhibited cognitive biases across a battery of tasks: framing bias appeared in both cognitive-emotional and purely cognitive tasks, consistent with previous studies. Language of presentation (and proficiency) did not have a significant effect on responses in cognitive-emotional tasks, but did have an effect on the purely-cognitive Disjunction fallacy task: HS speakers did better in their second, more proficient language, a result consistent with neither the reduced emotionality hypothesis nor the cognitive enhancement hypothesis. Moreover, higher proficiency in Spanish significantly improved the rate of correct responses, indicating that our results are more consistent with the cognitive overload hypothesis.
The Role of Acoustic Similarity and Non-Native Categorisation in Predicting Non-Native Discrimination: Brazilian Portuguese Vowels by English vs. Spanish Listeners
Authors: Elvin Jaydene , Williams Daniel , Shaw Jason A. , Best Catherine T. , Escudero Paola
Published: March 2021

This study tests whether Australian English (AusE) and European Spanish (ES) listeners differ in their categorisation and discrimination of Brazilian Portuguese (BP) vowels. In particular, we investigate two theoretically relevant measures of vowel category overlap (acoustic vs. perceptual categorisation) as predictors of non-native discrimination difficulty. We also investigate whether the individual listener’s own native vowel productions predict non-native vowel perception better than group averages. The results showed comparable performance for AusE and ES participants in their perception of the BP vowels. In particular, discrimination patterns were largely dependent on contrast-specific learning scenarios, which were similar across AusE and ES. We also found that acoustic similarity between individuals’ own native productions and the BP stimuli were largely consistent with the participants’ patterns of non-native categorisation. Furthermore, the results indicated that both acoustic and perceptual overlap successfully predict discrimination performance. However, accuracy in discrimination was better explained by perceptual similarity for ES listeners and by acoustic similarity for AusE listeners. Interestingly, we also found that for ES listeners, the group averages explained discrimination accuracy better than predictions based on individual production data, but that the AusE group showed no difference.
Phenothiazines Modified with the Pyridine Ring as Promising Anticancer Agents
Authors: Morak-Młodawska Beata , Jeleń Małgorzata , Pluta Krystian
Published: March 2021

Azaphenothiazines are the largest and most perspective group of modified phenothiazines, and they exhibit variety of biological activities. The review sums up the current knowledge on the anticancer activity of isomeric pyridobenzothiazines and dipyridothiazines, which are modified azaphenothiazines with one and two pyridine rings, respectively, against 10 types of cancer cell lines. Some 10-substituted dipyridothiazines and even 10-unsubstituted parent compounds, such as 10H-1,9-diazaphenothiazine and 10H-3,6-diazaphenothiazine, exhibited very potent action with the IC50 values less than 1 µg/mL and 1 µM against selected cancer cell lines. The strength of the anticancer action depends both on the tricyclic ring scaffolds and the substituents at the thiazine nitrogen atom. The review discusses the kind of the substituents, nature of tricyclic ring scaffolds with the location of the azine nitrogen atoms, the types of the cancer cell lines, and the mechanism of action.
Single-Component Organic Solar Cells Based on Intramolecular Charge Transfer Photoabsorption
Authors: Nakayama Ken-ichi , Okura Tatsuya , Okuda Yuki , Matsui Jun , Masuhara Akito , Yoshida Tsukasa , White Matthew Schuette , Yumusak Cigdem , Stadler Phillip , Scharber Markus , Sariciftci Niyazi Serdar
Published: March 2021

Conjugated donor–acceptor molecules with intramolecular charge transfer absorption are employed for single-component organic solar cells. Among the five types of donor–acceptor molecules, the strong push–pull structure of DTDCPB resulted in solar cells with high JSC, an internal quantum efficiency exceeding 20%, and high VOC exceeding 1 V with little photon energy loss around 0.7 eV. The exciton binding energy (EBE), which is a key factor in enhancing the photocurrent in the single-component device, was determined by quantum chemical calculation. The relationship between the photoexcited state and the device performance suggests that the strong internal charge transfer is effective for reducing the EBE. Furthermore, molecular packing in the film is shown to influence photogeneration in the film bulk.
Characterization of a New Lightened Gypsum-Based Material Reinforced with Fibers
Authors: Álvarez Manuel , Ferrández Daniel , Morón Carlos , Atanes-Sánchez Evangelina
Published: March 2021

This paper shows the characterization of a new lightened gypsum-based material for use in buildings. A plaster material has been designed with a polymeric compound based on polyvinyl acetate, bicarbonate and a boric acid solution, which reduce the density and thermal conductivity by up to 20% and 30%, respectively. In addition, tests have been carried out with the lightened plaster material reinforced with glass (GF), basalt (BF), polypropylene (PPF) and wood (WF) fibers. A significant improvement in mechanical properties was achieved. All samples obtained resistance values greater than 2 MPa in flexion and 3 MPa in compression. Physico-chemical analysis were also carried out. The study is completed with a statistical analysis, where confidence intervals have been obtained for the mean at 95% confidence for each of the physical properties studied.
Strengthening and Weakening Effects of Particles on Strength and Ductility of SiC Particle Reinforced Al-Cu-Mg Alloys Matrix Composites
Authors: Yang Zhiyu , Fan Jianzhong , Liu Yanqiang , Nie Junhui , Yang Ziyue , Kang Yonglin
Published: March 2021

The strengthening and weakening effects of SiC particles on composite strength and ductility were studied. Al-Cu-Mg alloys matrices with three different mechanical properties were used. Their yield strength, ultimate strength, and elongation range from 90 to 379 MPa, 131 to 561 MPa, and 18% to 31%, respectively. SiC particles with sizes of 4, 8, 12, 15, 20, and 30 μm were used to reinforce these three matrices, separately, and the composites of eighteen combinations of the particle sizes and matrix strengths were manufactured. Yield strength, ultimate strength, elongation, and fracture morphology of these composites were characterized. Based on the analysis, the strengthening to weakening behavior on strength and ductility were comprehensively discussed. The critical particle size having the best ductility was obtained. The strengthening limit and match range of the particle and the matrix to achieve effective strengthening were defined as a function of the particle size and matrix strength. This work offers an important reference for optimization of mechanical properties of the particle-reinforced metal matrix composites.
Mechanical Properties of the Interfacial Bond between Asphalt-Binder and Aggregates under Different Aging Conditions
Authors: Zhang Xiaorui , Wang Juntian , Zhou Xinxing , Zhang Zhuqiu , Chen Xiaobing
Published: March 2021

Aging has a detrimental impact on the interfacial interaction and bonding between asphalt-binder and aggregates, which influence ultimately on the performance of asphalt mixtures and pavements. Evaluation of the mechanical properties of the interface between the asphalt-binder and aggregates has thus become a hot research topic, particularly as a function of aging. In this study, the interfacial tensile strength, compressive strength, elastic modulus, and interfacial recovery energy were measured and quantified using molecular dynamic simulation. Whilst the free volume of the asphalt mixtures exhibited sensitivity to aging, the interfacial tensile strength decreased with an increase in the degree of aging. In general, the mechanical properties of the asphalt-binder-aggregate interface were found to be significantly dependent on the aggregate type. Furthermore, the study results indicated that interfacial recovery energy is a key characteristic property for characterizing the interfacial adhesive force within asphalt mixtures. Overall, the study of mechanical properties of the asphalt-binder and aggregate interface, as presented in this paper, contributes to quantifying the adhesive properties and improving the performance of asphalt mixtures.
Structural and Secondary Electron Yield Properties of Titanium–Palladium Films with Laser-Treated Copper Substrate for Application in Neutron Generators
Authors: Gao Yong , Wang Sheng , Wang Jie , You Zhiming , Zhang Jing , Hu Yaocheng , Wu Yue , Fan Jiakun , Li Haipeng , Zhan Qin , Yang Hongguang , Xu Zhanglian
Published: March 2021

Secondary electron emission (SEE) of the oxygen-free high-conductivity copper (OFHC) target surface in neutron generators limits the stability and improvement of the neutron yield. A novel-type target of titanium–palladium films coated on laser-treated OFHC target substrate was proposed and explored in this work to obtain low secondary electron yield (SEY) without introducing any components. The combination of Ti–Pd films and laser-treated OFHC substrate can effectively suppress secondary electron emission and enhance the adsorption ability to hydrogen isotopes with the existence of Pd film. The surface morphologies, surface chemical states, and SEYs of Ti–Pd films with laser-treated OFHC substrate were studied systematically for the first time. The XPS results showed that the laser-treated OFHC substrate surface was basically covered by Pd film. However, the Pd film surface was partially oxidized, with percentages of 21.31 and 10.02% for PdO and PdO2, respectively. The SEYs of Ti–Pd films with laser-treated OFHC substrate were all below 1 within the investigated primary energy range of 100–3000 eV, which would be sufficient for application in neutron generators. Specifically, the maximum SEY (δmax) of laser-treated OFHC substrate coated by Ti–Pd films was 0.87 with corresponding incident electron energy of 400 eV.
Formulation of Strain Fatigue Criterion Based on Complex Numbers
Authors: Łagoda Tadeusz , Głowacka Karolina , Kurek Marta , Skibicki Dariusz
Published: March 2021

In the case of many low-cycle multiaxial fatigue criteria, we encounter a mathematical problem of adding vectors of normal and shear strains. Typically, the problem of defining an equivalent strain is solved by weighting factors. Unfortunately, this ignores the fact that these vectors represent other physical quantities: the normal strain is a longitudinal strain, and the shear strain is a rotation angle. Therefore, the goal of the present work was to propose a method of combining different types of strains by adopting a system of complex numbers. The normal strain was defined as the real part and the shear strain was defined as the imaginary part. Using this approach, simple load states, such as pure bending and pure torsion, have been transformed into an expression for equivalent strain identical to the previously proposed criteria defined by Macha.
High Power Impulse Magnetron Sputtering of In2O3/Sn Cold Sprayed Composite Target
Authors: Winnicki Marcin , Wiatrowski Artur , Mazur Michał
Published: March 2021

High Power Impulse Magnetron Sputtering (HiPIMS) was used for deposition of indium tin oxide (ITO) transparent thin films at low substrate temperature. A hybrid-type composite target was self-prepared by low-pressure cold spraying process. Prior to spraying In2O3 and oxidized Sn powders were mixed in a volume ratio of 3:1. Composite In2O3/Sn coating had a mean thickness of 900 µm. HiPIMS process was performed in various mixtures of Ar:O2: (i) 100:0 vol.%, (ii) 90:10 vol.%, (iii) 75:25 vol.%, (iv) 50:50 vol.%, and (v) 0:100 vol.%. Oxygen rich atmosphere was necessary to oxidize tin atoms. Self-design, simple high voltage power switch capable of charging the 20 µF capacitor bank from external high voltage power supply worked as a power supply for an unbalanced magnetron source. ITO thin films with thickness in the range of 30–40 nm were obtained after 300 deposition pulses of 900 V and deposition time of 900 s. The highest transmission of 88% at λ = 550 nm provided 0:100 vol. % Ar:O2 mixture, together with the lowest resistivity of 0.03 Ω·cm.
Influence of Pulse Current Forward-Reverse Duty Cycle on Structure and Performance of Electroplated W–Cu Composite Coatings
Authors: Zhao Yuchao , Ye Nan , Zhuo Haiou , Wei Chaolong , Zhou Weiwei , Mao Jie , Tang Jiancheng
Published: March 2021

Tungsten-copper (W–Cu) composites are widely used as electrical contact materials, resistance welding, electrical discharge machining (EDM), and plasma electrode materials due to their excellent arc erosion resistance, fusion welding resistance, high strength, and superior hardness. However, the traditional preparation methods pay little attention to the compactness and microstructural uniformity of W–Cu composites. Herein, W–Cu composite coatings are prepared by pulse electroplating using nano-W powder as raw material and the influence of forward-reverse duty cycle of pulse current on the structure and mechanical properties is systematically investigated. Moreover, the densification mechanism of the W–Cu composite coating is analyzed from the viewpoints of forward-pulse plating and reverse-pulse plating. At the current density (J) of 2 A/dm2, frequency (f) of 1500 Hz, forward duty cycle (df) of 40% and reverse duty cycle (dr) of 10%, the W–Cu composite coating rendered a uniform microstructure and compact structure, resulting in a hardness of 127 HV and electrical conductivity of 53.7 MS/m.
Minimum Mapping from EMG Signals at Human Elbow and Shoulder Movements into Two DoF Upper-Limb Robot with Machine Learning
Authors: Laksono Pringgo Widyo , Kitamura Takahide , Muguro Joseph , Matsushita Kojiro , Sasaki Minoru , Amri bin Suhaimi Muhammad Syaiful
Published: March 2021

This research focuses on the minimum process of classifying three upper arm movements (elbow extension, shoulder extension, combined shoulder and elbow extension) of humans with three electromyography (EMG) signals, to control a 2-degrees of freedom (DoF) robotic arm. The proposed minimum process consists of four parts: time divisions of data, Teager–Kaiser energy operator (TKEO), the conventional EMG feature extraction (i.e., the mean absolute value (MAV), zero crossings (ZC), slope-sign changes (SSC), and waveform length (WL)), and eight major machine learning models (i.e., decision tree (medium), decision tree (fine), k-Nearest Neighbor (KNN) (weighted KNN, KNN (fine), Support Vector Machine (SVM) (cubic and fine Gaussian SVM), Ensemble (bagged trees and subspace KNN). Then, we compare and investigate 48 classification models (i.e., 47 models are proposed, and 1 model is the conventional) based on five healthy subjects. The results showed that all the classification models achieved accuracies ranging between 74–98%, and the processing speed is below 40 ms and indicated acceptable controller delay for robotic arm control. Moreover, we confirmed that the classification model with no time division, with TKEO, and with ensemble (subspace KNN) had the best performance in accuracy rates at 96.67, recall rates at 99.66, and precision rates at 96.99. In short, the combination of the proposed TKEO and ensemble (subspace KNN) plays an important role to achieve the EMG classification.
Combined Games with Randomly Delayed Beginnings
Authors: Bruss F. Thomas
Published: March 2021

This paper presents two-person games involving optimal stopping. As far as we are aware, the type of problems we study are new. We confine our interest to such games in discrete time. Two players are to chose, with randomised choice-priority, between two games G1 and G2. Each game consists of two parts with well-defined targets. Each part consists of a sequence of random variables which determines when the decisive part of the game will begin. In each game, the horizon is bounded, and if the two parts are not finished within the horizon, the game is lost by definition. Otherwise the decisive part begins, on which each player is entitled to apply their or her strategy to reach the second target. If only one player achieves the two targets, this player is the winner. If both win or both lose, the outcome is seen as “deuce”. We motivate the interest of such problems in the context of real-world problems. A few representative problems are solved in detail. The main objective of this article is to serve as a preliminary manual to guide through possible approaches and to discuss under which circumstances we can obtain solutions, or approximate solutions.
One Type of Symmetric Matrix with Harmonic Pell Entries, Its Inversion, Permanents and Some Norms
Authors: Yamaç Akbiyik Seda , Akbiyik Mücahit , Yilmaz Fatih
Published: March 2021

The Pell numbers, named after the English diplomat and mathematician John Pell, are studied by many authors. At this work, by inspiring the definition harmonic numbers, we define harmonic Pell numbers. Moreover, we construct one type of symmetric matrix family whose elements are harmonic Pell numbers and its Hadamard exponential matrix. We investigate some linear algebraic properties and obtain inequalities by using matrix norms. Furthermore, some summation identities for harmonic Pell numbers are obtained. Finally, we give a MATLAB-R2016a code which writes the matrix with harmonic Pell entries and calculates some norms and bounds for the Hadamard exponential matrix.
Qualitative Properties of Randomized Maximum Entropy Estimates of Probability Density Functions
Authors: Popkov Yuri S.
Published: March 2021

The problem of randomized maximum entropy estimation for the probability density function of random model parameters with real data and measurement noises was formulated. This estimation procedure maximizes an information entropy functional on a set of integral equalities depending on the real data set. The technique of the Gâteaux derivatives is developed to solve this problem in analytical form. The probability density function estimates depend on Lagrange multipliers, which are obtained by balancing the model’s output with real data. A global theorem for the implicit dependence of these Lagrange multipliers on the data sample’s length is established using the rotation of homotopic vector fields. A theorem for the asymptotic efficiency of randomized maximum entropy estimate in terms of stationary Lagrange multipliers is formulated and proved. The proposed method is illustrated on the problem of forecasting of the evolution of the thermokarst lake area in Western Siberia.
On the Similarity and Dependence of Time Series
Authors: Novák Vilém , Mirshahi Soheyla
Published: March 2021

In this paper, we undertake the problem of evaluating interrelation among time series. Interrelation is measured using a similarity index. In this paper, we suggest a new one based on the known fuzzy transform (F-transform), which has been proven to remove higher frequencies than a given threshold and reduce the random noise significantly. The F-transform also provides an estimation of the slope of time series in a given imprecisely delineated time. We prove some of the suggested index properties and show its ability to measure similarity (and thus the interrelation) on a selection of several real financial time series. The method is well interpretable and easy to adjust.
Improving the Accuracy of Dam Inflow Predictions Using a Long Short-Term Memory Network Coupled with Wavelet Transform and Predictor Selection
Authors: Tran Trung Duc , Tran Vinh Ngoc , Kim Jongho
Published: March 2021

Accurate and reliable dam inflow prediction models are essential for effective reservoir operation and management. This study presents a data-driven model that couples a long short-term memory (LSTM) network with robust input predictor selection, input reconstruction by wavelet transformation, and efficient hyper-parameter optimization by K-fold cross-validation and the random search. First, a robust analysis using a “correlation threshold” for partial autocorrelation and cross-correlation functions is proposed, and only variables greater than this threshold are selected as input predictors and their time lags. This analysis indicates that a model trained on a threshold of 0.4 returns the highest Nash–Sutcliffe efficiency value; as a result, six principal inputs are selected. Second, using additional subseries reconstructed by the wavelet transform improves predictability, particularly for flow peak. The peak error values of LSTM with the transform are approximately one-half to one-quarter the size of those without the transform. Third, for a K of 5 as determined by the Silhouette coefficients and the distortion score, the wavelet-transformed LSTMs require a larger number of hidden units, epochs, dropout, and batch size. This complex configuration is needed because the amount of inputs used by these LSTMs is five times greater than that of other models. Last, an evaluation of accuracy performance reveals that the model proposed in this study, called SWLSTM, provides superior predictions of the daily inflow of the Hwacheon dam in South Korea compared with three other LSTM models by 84%, 78%, and 65%. These results strengthen the potential of data-driven models for efficient and effective reservoir inflow predictions, and should help policy-makers and operators better manage their reservoir operations.
Oscillation Criteria for Third-Order Nonlinear Neutral Dynamic Equations with Mixed Deviating Arguments on Time Scales
Authors: Zhang Zhiyu , Feng Ruihua , Jadlovská Irena , Liu Qingmin
Published: March 2021

Under a couple of canonical and mixed canonical-noncanonical conditions, we investigate the oscillation and asymptotic behavior of solutions to a class of third-order nonlinear neutral dynamic equations with mixed deviating arguments on time scales. By means of the double Riccati transformation and the inequality technique, new oscillation criteria are established, which improve and generalize related results in the literature. Several examples are given to illustrate the main results.
Experimental Analysis and Optimization of EDM Parameters on HcHcr Steel in Context with Different Electrodes and Dielectric Fluids Using Hybrid Taguchi-Based PCA-Utility and CRITIC-Utility Approaches
Authors: Patel Gowdru Chandrashekarappa Manjunath , Kumar Sandeep , Jagadish Jagadish , Pimenov Danil Yurievich , Giasin Khaled
Published: March 2021

Industries demand stringent requirements towards economical machining without hindering the surface quality while cutting high carbon high chromium (HcHcr) steel. Electrical discharge machining (EDM) of HcHcr steel aims at reducing machining cost (i.e., maximize material removal rate (MRR) and minimize tool wear rate (TWR)) with good surface quality (i.e., minimize surface roughness (SR)). A comparative study was carried out on EDM of HcHcr D2 steel (DIN EN ISO 4957) by applying Taguchi L18 experimental design considering different electrode materials (copper, graphite, and brass), dielectric fluids (distilled water and kerosene), peak current, and pulse-on-time. The process performances were analyzed with respect to material removal rate, surface roughness, and tool wear rate. Pareto analysis of variance was employed to estimate the significance of the process variables and their optimal levels for achieving lower SR and TWR and higher MRR. Hybrid Taguchi-CRITIC-Utility and Taguchi-PCA-Utility methods were implemented to determine the optimal EDM parameters. Higher MRR of 0.0632 g/min and lower SR of 1.68 µm and TWR of 0.012 g/min was attained by graphite electrode in presence of distilled water as dielectric fluid compared to the brass and copper. Additionally, a metallographic analysis was carried out to study the surface integrity on the machined surfaces. Micrographic analysis of the optimal conditions showed lower surface roughness and fewer imperfections (lesser impression, waviness surface, and micro-cracks) compared to worst conditions.
A Sample-In-Answer-Out Microfluidic System for the Molecular Diagnostics of 24 HPV Genotypes Using Palm-Sized Cartridge
Authors: Wang Rui , Wu Jing , He Xiaodong , Zhou Peng , Shen Zuojun
Published: March 2021

This paper proposes an automated microfluidic system for molecular diagnostics that integrates the functions of a traditional polymerase chain reaction (PCR) laboratory into a palm-sized microfluidic cartridge (CARD) made of polystyrene. The CARD integrates 4 independent microfluidic sample lanes, which can independently complete a sample test, and each sample lane integrates the 3 functional areas of the sample preparation area, PCR amplification area, and product analysis area. By using chemical cell lysis, magnetic silica bead-based DNA extraction, combined with multi-PCR-reverse dot hybridization with microarray, 24 HPV genotypes can be typing tested in CARD. With a custom-made automated CARD operating platform, the entire process can be automatically carried out, achieving sample-in-answer-out. The custom-made operation platform is developed based on a liquid handling station-type, which can automatically load off-chip reagents without placing reagents in CARD in advance. The platform can control six CARDs to work simultaneously, detect 24 samples at a time. The results show that the limit of detection of the microfluidic system is 200 copies/test, and the positive detection rate of clinical samples by this system is 100%, which is an effective method for detection of HPV.
Raman Mapping of Biological Systems Interacting with a Disordered Nanostructured Surface: A Simple and Powerful Approach to the Label-Free Analysis of Single DNA Bases
Authors: Mussi Valentina , Ledda Mario , Convertino Annalisa , Lisi Antonella
Published: March 2021

This article demonstrates the possibility to use a novel powerful approach based on Raman mapping of analyte solutions drop casted on a disordered array of Ag covered silicon nanowires (Ag/SiNWs), to identify the characteristic spectral signal of the four DNA bases, adenine (A), thymine (T), cytosine (C), and guanine (G), at concentration as low as 10 ng/µL, and to study their specific way of interacting with the nanostructured substrate. The results show a distinctive and amplified interaction of guanine, the base that is most susceptible to oxidation, with the nanostructured surface. Our findings explain the recently revealed diverse behaviour of cancer and normal DNA deposited on the same Ag/SiNWs, which is ascribed to mechanical deformation and base lesions present on the oxidised DNA molecule backbone and causes detectable variation in the Raman signal, usable for diagnostic purposes. The notable bio-analytical capability of the presented platform, and its sensitivity to the molecule mechanical conformation at the single-base level, thus provides a new reliable, rapid, label-free DNA diagnostic methodology alternative to more sophisticated and expensive sequencing ones.
Effect of Surface Microstructure on the Heat Dissipation Performance of Heat Sinks Used in Electronic Devices
Authors: You Yuxin , Zhang Beibei , Tao Sulian , Liang Zihui , Tang Biao , Zhou Rui , Yuan Dong
Published: March 2021

Heat sinks are widely used in electronic devices with high heat flux. The design and build of microstructures on heat sinks has shown effectiveness in improving heat dissipation efficiency. In this paper, four kinds of treatment methods were used to make different microstructures on heat sink surfaces, and thermal radiation coating also applied onto the heat sink surfaces to improve thermal radiation. The surface roughness, thermal emissivity and heat dissipation performance with and without thermal radiation coating of the heat sinks were studied. The result shows that with an increase of surface roughness, the thermal emissivity can increase up to 2.5 times. With thermal radiation coating on a surface with microstructures, the heat dissipation was further improved because the heat conduction at the coating and heat sink interface was enhanced. Therefore, surface treatment can improve the heat dissipation performance of the heat sink significantly by enhancing the thermal convection, radiation and conduction.
The Adult Phenylketonuria (PKU) Gut Microbiome
Authors: Mancilla Viviana J. , Mann Allison E. , Zhang Yan , Allen Michael S.
Published: March 2021

Phenylketonuria (PKU) is an inborn error of phenylalanine metabolism primarily treated through a phenylalanine-restrictive diet that is frequently supplemented with an amino acid formula to maintain proper nutrition. Little is known of the effects of these dietary interventions on the gut microbiome of PKU patients, particularly in adults. In this study, we sequenced the V4 region of the 16S rRNA gene from stool samples collected from adults with PKU (n = 11) and non-PKU controls (n = 21). Gut bacterial communities were characterized through measurements of diversity and taxa abundance. Additionally, metabolic imputation was performed based on detected bacteria. Gut community diversity was lower in PKU individuals, though this effect was only statistically suggestive. A total of 65 genera across 5 phyla were statistically differentially abundant between PKU and control samples (p < 0.001). Additionally, we identified six metabolic pathways that differed between groups (p < 0.05), with four enriched in PKU samples and two in controls. While the child PKU gut microbiome has been previously investigated, this is the first study to explore the gut microbiome of adult PKU patients. We find that microbial diversity in PKU children differs from PKU adults and highlights the need for further studies to understand the effects of dietary restrictions.
Prospection of Fungal Lignocellulolytic Enzymes Produced from Jatoba (Hymenaea courbaril) and Tamarind (Tamarindus indica) Seeds: Scaling for Bioreactor and Saccharification Profile of Sugarcane Bagasse
Authors: Contato Alex Graça , de Oliveira Tássio Brito , Aranha Guilherme Mauro , de Freitas Emanuelle Neiverth , Vici Ana Claudia , Nogueira Karoline Maria Vieira , de Lucas Rosymar Coutinho , Scarcella Ana Sílvia de Almeida , Buckeridge Marcos Silveira , Silva Roberto Nascimento , Polizeli Maria de Lourdes Teixeira de Moraes
Published: March 2021

The lignocellulosic biomass comprises three main components: cellulose, hemicellulose, and lignin. Degradation and conversion of these three components are attractive to biotechnology. This study aimed to prospect fungal lignocellulolytic enzymes with potential industrial applications, produced through a temporal analysis using Hymenaea courbaril and Tamarindus indica seeds as carbon sources. α-L-arabinofuranosidase, acetyl xylan esterase, endo-1,5-α-L-arabinanase, β-D-galactosidase, β-D-glucosidase, β-glucanase, β-D-xylosidase, cellobiohydrolase, endoglucanase, lichenase, mannanase, polygalacturonase, endo-1,4-β-xylanase, and xyloglucanase activities were determined. The enzymes were produced for eight filamentous fungi: Aspergillus fumigatus, Trametes hirsuta, Lasiodiplodia sp., two strains of Trichoderma longibrachiatum, Neocosmospora perseae, Fusarium sp. and Thermothelomyces thermophilus. The best producers concerning enzymatic activity were T. thermophilus and T. longibrachiatum. The optimal conditions for enzyme production were the media supplemented with tamarind seeds, under agitation, for 72 h. This analysis was essential to demonstrate that cultivation conditions, static and under agitation, exert strong influences on the production of several enzymes produced by different fungi. The kind of sugarcane, pretreatment used, microorganisms, and carbon sources proved limiting sugar profile factors.