bluuebunny/crossref_metadata_2025 huggingface dataset:
Algorithm for Preventing the Spread of COVID-19 in Airports and Air Routes by Applying Fuzzy Logic and a Markov Chain
Authors: Guevara Cesar , Bonilla Diego
Published: November 2021

Since the start of COVID-19 and its growth into an uncontrollable pandemic, the spread of diseases through airports has become a serious health problem around the world. This study presents an algorithm to determine the risk of spread in airports and air routes. Graphs are applied to model the air transport network and Dijkstra’s algorithm is used for generating routes. Fuzzy logic is applied to evaluate multiple demographics, health, and transport variables and identify the level of spread in each airport. The algorithm applies a Markov chain to determine the probability of the arrival of an infected passenger with the COVID-19 virus to an airport in any country in the world. The results show the optimal performance of the proposed algorithm. In addition, some data are presented that allow for the application of actions in health and mobility policies to prevent the spread of infectious diseases.
A High-Resolution Dyadic Transform for Non-Stationary Signal Analysis
Authors: Trutié-Carrero Eduardo , Seuret-Jiménez Diego , Nieto-Jalil José M.
Published: November 2021

This article shows a new Te-transform and its periodogram for applications that mainly exhibit stochastic behavior with a signal-to-noise ratio lower than −30 dB. The Te-transform is a dyadic transform that combines the properties of the dyadic Wavelet transform and the Fourier transform. This paper also provides another contribution, a corollary on the energy relationship between the untransformed signal and the transformed one using the Te-transform. This transform is compared with other methods used for the analysis in the frequency domain, reported in literature. To perform the validation, the authors created two synthetic scenarios: a noise-free signal scenario and another signal scenario with a signal-to-noise ratio equal to −69 dB. The results show that the Te-transform improves the sensitivity in the frequency spectrum with respect to previously reported methods.
Predicate-Based Model of Problem-Solving for Robotic Actions Planning
Authors: Tsymbal Oleksandr , Mercorelli Paolo , Sergiyenko Oleg
Published: November 2021

The aim of the article is to describe a predicate-based logical model for the problem-solving of robots. The proposed article deals with analyses of trends of problem-solving robotic applications for manufacturing, especially for transportations and manipulations. Intelligent agent-based manufacturing systems with robotic agents are observed. The intelligent cores of them are considered from point of view of ability to propose the plans of problem-solving in the form of strategies. The logical model of adaptive strategies planning for the intelligent robotic system is composed in the form of predicates with a presentation of data processing on a base of set theory. The dynamic structures of workspaces, and a possible change of goals are considered as reasons for functional strategies adaptation.
Fuzzy Branch-and-Bound Algorithm with OWA Operators in the Case of Consumer Decision Making
Authors: Vizuete-Luciano Emili , Boria-Reverter Sefa , Merigó-Lindahl José M. , Gil-Lafuente Anna Maria , Solé-Moro Maria Luisa
Published: November 2021

The ordered weighted averaging (OWA) operator is one of the most used techniques in the operator’s aggregation procedure. This paper proposes a new assignment algorithm by using the OWA operator and different extensions of it in the Branch-and-bound algorithm. The process is based on the use of the ordered weighted average distance operator (OWAD) and the induced OWAD operator (IOWAD). We present it as the Branch-and-bound algorithm with the OWAD operator (BBAOWAD) and the Branch-and-bound algorithm with the IOWAD operator (BBAIOWAD). The main advantage of this approach is that we can obtain more detailed information by obtaining a parameterized family of aggregation operators. The application of the new algorithm is developed in a consumer decision-making model in the city of Barcelona regarding the selection of groceries by districts that best suit their needs. We rely on the opinion of local commerce experts in the city. The key advantage of this approach is that we can consider different sources of information independent of each other.
Steffensen-Type Inequalities with Weighted Function via (γ, a)-Nabla-Conformable Integral on Time Scales
Authors: El-Deeb Ahmed A. , Awrejcewicz Jan
Published: November 2021

The primary goal of this our research is to prove several new ∇-conformable dynamic Steffensen inequalities that were demonstrated in recent works. Our results generalize and extend existing results in the literature. Many special cases of the proposed results are obtained and analyzed such as new conformable fractional sum inequalities and new classical conformable fractional integral inequalities.
Flow and Heat Transfer Past a Stretching/Shrinking Sheet Using Modified Buongiorno Nanoliquid Model
Authors: Roşca Natalia C. , Roşca Alin V. , Aly Emad H. , Pop Ioan
Published: November 2021

This paper studies the boundary layer flow and heat transfer characteristics past a permeable isothermal stretching/shrinking surface using both nanofluid and hybrid nanofluid flows (called modified Buongiorno nonliquid model). Using appropriate similarity variables, the PDEs are transformed into ODEs to be solved numerically using the function bvp4c from MATLAB. It was found that the solutions of the resulting system have two branches, upper and lower branch solutions, in a certain range of the suction, stretching/shrinking and hybrid nanofluids parameters. Both the analytic and numerical results are obtained for the skin friction coefficient, local Nusselt number, and velocity and temperature distributions, for several values of the governing parameters. It results in the governing parameters considerably affecting the flow and heat transfer characteristics.
F4: An All-Purpose Tool for Multivariate Time Series Classification
Authors: López-Oriona Ángel , Vilar José A.
Published: November 2021

We propose Fast Forest of Flexible Features (F4), a novel approach for classifying multivariate time series, which is aimed to discriminate between underlying generating processes. This goal has barely been addressed in the literature. F4 consists of two steps. First, a set of features based on the quantile cross-spectral density and the maximum overlap discrete wavelet transform are extracted from each series. Second, a random forest is fed with the extracted features. An extensive simulation study shows that F4 outperforms some powerful classifiers in a wide variety of situations, including stationary and nonstationary series. The proposed method is also capable of successfully discriminating between electrocardiogram (ECG) signals of healthy subjects and those with myocardial infarction condition. Additionally, despite lacking shape-based information, F4 attains state-of-the-art results in some datasets of the University of East Anglia (UEA) multivariate time series classification archive.
Alias Structures and Sequential Experimentation for Mixed-Level Designs
Authors: Ríos-Lira Armando Javier , Pantoja-Pacheco Yaquelin Verenice , Vázquez-López José Antonio , Jiménez-García José Alfredo , Asato-España Martha Laura , Tapia-Esquivias Moisés
Published: November 2021

Alias structures for two-level fractional designs are commonly used to describe the correlations between different terms. The concept of alias structures can be extended to other types of designs such as fractional mixed-level designs. This paper proposes an algorithm that uses the Pearson’s correlation coefficient and the correlation matrix to construct alias structures for these designs, which can help experimenters to more easily visualize which terms are correlated (or confounded) in the mixed-level fraction and constitute the basis for efficient sequential experimentation.
A High-Dimensional Counterpart for the Ridge Estimator in Multicollinear Situations
Authors: Arashi Mohammad , Norouzirad Mina , Roozbeh Mahdi , Khan Naushad Mamode
Published: November 2021

The ridge regression estimator is a commonly used procedure to deal with multicollinear data. This paper proposes an estimation procedure for high-dimensional multicollinear data that can be alternatively used. This usage gives a continuous estimate, including the ridge estimator as a particular case. We study its asymptotic performance for the growing dimension, i.e., p→∞ when n is fixed. Under some mild regularity conditions, we prove the proposed estimator’s consistency and derive its asymptotic properties. Some Monte Carlo simulation experiments are executed in their performance, and the implementation is considered to analyze a high-dimensional genetic dataset.
Heat Kernels Estimates for Hermitian Line Bundles on Manifolds of Bounded Geometry
Authors: Kordyukov Yuri A.
Published: November 2021

We consider a family of semiclassically scaled second-order elliptic differential operators on high tensor powers of a Hermitian line bundle (possibly, twisted by an auxiliary Hermitian vector bundle of arbitrary rank) on a Riemannian manifold of bounded geometry. We establish an off-diagonal Gaussian upper bound for the associated heat kernel. The proof is based on some tools from the theory of operator semigroups in a Hilbert space, results on Sobolev spaces adapted to the current setting, and weighted estimates with appropriate exponential weights.
An Agent-Based Model-Driven Decision Support System for Assessment of Agricultural Vulnerability of Sugarcane Facing Climatic Change
Authors: Badillo-Márquez Alina Evelyn , Aguilar-Lasserre Alberto Alfonso , Miranda-Ackerman Marco Augusto , Sandoval-González Oscar Osvaldo , Villanueva-Vásquez Daniel , Posada-Gómez Rubén
Published: November 2021

In recent years, there have been significant changes in weather patterns, mainly caused by sharp increases in temperature, increases in carbon dioxide, and fluctuations in precipitation levels, negatively impacting agricultural production. Agricultural systems are characterized by being vulnerable to the variation of biophysical and socioeconomic factors involved in the development of agricultural activities. Agent-based models (ABMs) enable the study, analysis, and management of ecosystems through their ability to represent networks and their spatial nature. In this research, an ABM is developed to evaluate the behavior and determine the vulnerability in the sugarcane agricultural system; allowing the capitalization of knowledge through characteristics such as social ability and autonomy of the modeled agents through fuzzy logic and system dynamics. The methodology used includes information networks for a dynamic assessment of agricultural risk modeled by time series, system dynamics, uncertain parameters, and experience; which are developed in three stages: vulnerability indicators, crop vulnerability, and total system vulnerability. The development of ABM, a greater impact on the environmental contingency is noted due to the increase in greenhouse gas emissions and the exponential increase in extreme meteorological phenomena threatening the cultivation of sugarcane, making the agricultural sector more vulnerable and reducing the yield of the harvest.
Generalisation of the Frobenius Formula in the Theory of Block Operators on Normed Spaces
Authors: Sidorov Nikolai A. , Dreglea Aliona I. , Sidorov Denis N.
Published: November 2021

The efficient construction and employment of block operators are vital for contemporary computing, playing an essential role in various applications. In this paper, we prove a generalisation of the Frobenius formula in the setting of the theory of block operators on normed spaces. A system of linear equations with the block operator acting in Banach spaces is considered. Existence theorems are proved, and asymptotic approximations of solutions in regular and irregular cases are constructed. In the latter case, the solution is constructed in the form of a Laurent series. The theoretical approach is illustrated with an example, the construction of solutions for a block equation leading to a method of solving some linear integrodifferential system.
A Scheduling Approach for the Combination Scheme and Train Timetable of a Heavy-Haul Railway
Authors: Zhou Hanxiao , Zhou Leishan , Guo Bin , Bai Zixi , Wang Zeyu , Yang Lu
Published: November 2021

Heavy-haul railway transport is a critical mode of regional bulk cargo transport. It dramatically improves the freight transport capacity of railway lines by combining several unit trains into one combined train. In order to improve the efficiency of the heavy-haul transport system and reduce the transportation cost, a critical problem involves arranging the combination scheme in the combination station (CBS) and scheduling the train timetable along the trains’ journey. With this consideration, this paper establishes two integer programming models in stages involving the train service plan problem (TSPP) model and train timetabling problem (TTP) model. The TSPP model aims to obtain a train service plan according to the freight demands by minimizing the operation cost. Based on the train service plan, the TTP model is to simultaneously schedule the combination scheme and train timetable, considering the utilization optimal for the CBS. Then, an effective hybrid genetic algorithm (HGA) is designed to solve the model and obtain the combination scheme and train timetable. Finally, some experiments are implemented to illustrate the feasibility of the proposed approaches and demonstrate the effectiveness of the HGA.
Statistical Inference for a General Family of Modified Exponentiated Distributions
Authors: Gómez-Déniz Emilio , Iriarte Yuri A. , Gómez Yolanda M. , Barranco-Chamorro Inmaculada , Gómez Héctor W.
Published: November 2021

In this paper, a modified exponentiated family of distributions is introduced. The new model was built from a continuous parent cumulative distribution function and depends on a shape parameter. Its most relevant characteristics have been obtained: the probability density function, quantile function, moments, stochastic ordering, Poisson mixture with our proposal as the mixing distribution, order statistics, tail behavior and estimates of parameters. We highlight the particular model based on the classical exponential distribution, which is an alternative to the exponentiated exponential, gamma and Weibull. A simulation study and a real application are presented. It is shown that the proposed family of distributions is of interest to applied areas, such as economics, reliability and finances.
A Simplified Lindstedt-Poincaré Method for Saving Computational Cost to Determine Higher Order Nonlinear Free Vibrations
Authors: Liu Chein-Shan , Chen Yung-Wei
Published: November 2021

In order to improve the Lindstedt-Poincaré method to raise the accuracy and the performance for the application to strongly nonlinear oscillators, a new analytic method by engaging in advance a linearization technique in the nonlinear differential equation is developed, which is realized in terms of a weight factor to decompose the nonlinear term into two sides. We expand the constant preceding the displacement in powers of the introduced parameter so that the coefficients can be determined to avoid the appearance of secular solutions. The present linearized Lindstedt-Poincaré method is easily implemented to provide accurate higher order analytic solutions of nonlinear oscillators, such as Duffing and van Der Pol nonlinear oscillators. The accuracy of analytic solutions is evaluated by comparing to the numerical results obtained from the fourth-order Runge-Kotta method. The major novelty is that we can simplify the Lindstedt-Poincaré method to solve strongly a nonlinear oscillator with a large vibration amplitude.
ILC for Non-Linear Hyperbolic Partial Difference Systems
Authors: Hamidaoui Meryem , Shao Cheng
Published: November 2021

This paper discusses the iterative learning control problem for a class of non-linear partial difference system hyperbolic types. The proposed algorithm is the PD-type iterative learning control algorithm with initial state learning. Initially, we introduced the hyperbolic system and the control law used. Subsequently, we presented some dilemmas. Then, sufficient conditions for monotone convergence of the tracking error are established under the convenient assumption. Furthermore, we give a detailed convergence analysis based on previously given lemmas and the discrete Gronwall’s inequality for the system. Finally, we illustrate the effectiveness of the method using a numerical example.
Characterization of Rectifying Curves by Their Involutes and Evolutes
Authors: Jianu Marilena , Achimescu Sever , Dăuş Leonard , Mihai Adela , Roman Olimpia-Alice , Tudor Daniel
Published: November 2021

A rectifying curve is a twisted curve with the property that all of its rectifying planes pass through a fixed point. If this point is the origin of the Cartesian coordinate system, then the position vector of the rectifying curve always lies in the rectifying plane. A remarkable property of these curves is that the ratio between torsion and curvature is a nonconstant linear function of the arc-length parameter. In this paper, we give a new characterization of rectifying curves, namely, we prove that a curve is a rectifying curve if and only if it has a spherical involute. Consequently, rectifying curves can be constructed as evolutes of spherical twisted curves; we present an illustrative example of a rectifying curve obtained as the evolute of a spherical helix. We also express the curvature and the torsion of a rectifying spherical curve and give necessary and sufficient conditions for a curve and its involute to be both rectifying curves.
A Generative Model for Correlated Graph Signals
Authors: Loskot Pavel
Published: November 2021

A graph signal is a random vector with a partially known statistical description. The observations are usually sufficient to determine marginal distributions of graph node variables and their pairwise correlations representing the graph edges. However, the curse of dimensionality often prevents estimating a full joint distribution of all variables from the available observations. This paper introduces a computationally effective generative model to sample from arbitrary but known marginal distributions with defined pairwise correlations. Numerical experiments show that the proposed generative model is generally accurate for correlation coefficients with magnitudes up to about 0.3, whilst larger correlations can be obtained at the cost of distribution approximation accuracy. The generative models of graph signals can also be used to sample multivariate distributions for which closed-form mathematical expressions are not known or are too complex.
Beyond Topological Persistence: Starting from Networks
Authors: Bergomi Mattia G. , Ferri Massimo , Vertechi Pietro , Zuffi Lorenzo
Published: November 2021

Persistent homology enables fast and computable comparison of topological objects. We give some instances of a recent extension of the theory of persistence, guaranteeing robustness and computability for relevant data types, like simple graphs and digraphs. We focus on categorical persistence functions that allow us to study in full generality strong kinds of connectedness—clique communities, k-vertex, and k-edge connectedness—directly on simple graphs and strong connectedness in digraphs.
Hyperbaric Oxygen Therapy with Iloprost Improves Digit Salvage in Severe Frostbite Compared to Iloprost Alone
Authors: Magnan Marie-Anne , Gayet-Ageron Angèle , Louge Pierre , Champly Frederic , Joffre Thierry , Lovis Christian , Pignel Rodrigue
Published: November 2021

Background and Objectives: Frostbite is a freezing injury that can lead to amputation. Current treatments include tissue rewarming followed by thrombolytic or vasodilators. Hyperbaric oxygen (HBO) therapy might decrease the rate of amputation by increasing cellular oxygen availability to the damaged tissues. The SOS-Frostbite study was implemented in a cross-border program among the hyperbaric centers of Geneva, Lyon, and the Mont-Blanc hospitals. The objective was to assess the efficacy of HBO + iloprost among patients with severe frostbite. Materials and Methods: We conducted a multicenter prospective single-arm study from 2013 to 2019. All patients received early HBO in addition to standard care with iloprost. Outcomes were compared to a historical cohort in which all patients received iloprost alone between 2000 and 2012. Inclusion criteria were stage 3 or 4 frostbite and initiation of medical care <72 h from frostbite injury. Outcomes were the number of preserved segments and the rate of amputated segments. Results: Thirty patients from the historical cohort were eligible and satisfied the inclusion criteria, and 28 patients were prospectively included. The number of preserved segments per patient was significantly higher in the prospective cohort (mean 13 ± SD, 10) compared to the historical group (6 ± 5, p = 0.006); the odds ratio was significantly higher by 45-fold (95%CI: 6-335, p < 0.001) in the prospective cohort compared to the historical cohort after adjustment for age and delay between signs of freezing and treatment start. Conclusions: This study demonstrates that the combination of HBO and iloprost was associated with higher benefit in patients with severe frostbite. The number of preserved segments was two-fold higher in the prospective cohort compared to the historical group (mean of 13 preserved segments vs. 6), and the reduction of amputation was greater in patients treated by HBO + iloprost compared with the iloprost only.
Severe Neonatal Anemia Due to Spontaneous Massive Fetomaternal Hemorrhage at Term: An Illustrative Case with Suspected Antenatal Diagnosis and Brief Review of Current Knowledge
Authors: Gică Nicolae , Botezatu Radu , Demetrian Mihaela , Vayna Ana Maria , Cimpoca-Raptis Brîndușa Ana , Ciobanu Anca Marina , Gica Corina , Peltecu Gheorghe , Panaitescu Anca Maria
Published: November 2021

Fetomaternal hemorrhage is defined as transfer of fetal blood into placental circulation and therefore into maternal circulation during pregnancy, and represents an important contributor to intrauterine fetal demise and neonatal death. The condition is rarely diagnosed prenatally because clinical findings are often nonspecific, and it is unpredictable. In this paper we present an illustrative case of massive spontaneous fetomaternal hemorrhage where the diagnosis was highly suspected antenatally based on maternal reported reduced fetal movements, abnormal suggestive cardiotocographic trace, and increased peak systolic velocity in the fetal middle cerebral artery. We discuss obstetrical and neonatal management and review the current knowledge in the literature. Maintaining a high index of suspicion for this condition allows the obstetrician to plan for adequate diagnostic tests, arrange intrauterine treatment or delivery, and prepare the neonatal team.
Drug-Induced Esophageal Ulcer in Adolescent Population: Experience at a Single Medical Center in Central Taiwan
Authors: Hu Shu-Wei , Chen An-Chyi , Wu Shu-Fen
Published: November 2021

Background and Objectives: Drug-induced esophageal ulcer is caused by focal drug stimulation. It may occur in adults and children. Limited research is available in pediatric patients with drug-induced esophageal ulcer; therefore, we designed this study to determine the characteristics of this disease in this population. Materials and Methods: Thirty-two pediatric patients diagnosed with drug-induced esophageal ulcers from a hospital database of upper gastrointestinal tract endoscopies were included. After treatment, patients were followed for 2 months after upper gastrointestinal endoscopy. Results: Female patients were predominant (56.2%/43.8%). The mean age of patients was 15.6 years (median, 16 years; interquartile range, 2 years). Doxycycline was administered in most cases (56.3%); other drugs were dicloxacillin, amoxicillin, clindamycin, L-arginine, and nonsteroidal anti-inflammatory drugs. Doxycycline was associated with kissing ulcers. Esophageal ulcers induced by nonsteroidal anti-inflammatory drugs were more often associated with gastric or duodenal ulcers. The most common location was the middle-third of the esophagus (78.1%). Patients were treated with proton pump inhibitors, sucralfate, or H2-blockers. The mean duration for which symptoms lasted was 9.2 days. No esophageal stricture was found in 24 patients who were followed for 2 months after upper gastrointestinal endoscopy. Conclusions: The authors suggest informing patients to take medicine with enough water (approximately 100 mL) and enough time (15–30 min) before recumbency, especially high-risk drugs, such as doxycycline or nonsteroidal anti-inflammatory drugs.
Influencing Factors on Person-Centered Care Competence among Nursing Students Experienced Clinical Training
Authors: Ahn Juhyun , Kim Myoungsuk
Published: November 2021

Background and Objectives: Nursing students require appropriate education to improve their person-centered care competence. Therefore, research on the various factors that influence person-centered care competence is necessary. This study aimed to identify factors influencing nursing professional values, satisfaction with major, and perception of the nursing profession on person-centered care competence. Materials and Methods: This study was a descriptive survey, and participants were nursing students from three universities in Korea. Structured self-report questionnaires were used for data collection. Results: Nursing professional values (p < 0.001) were found to be an influencing factor on person-centered care competence (Adjusted R2 = 0.244). However, the perception of the nursing profession, and the satisfaction with the major were not found to be significant influencing factors on person-centered care competence. Conclusions: The findings suggest that fostering nursing professional values in nursing students and developing educational interventions for the same are essential to improve person-centered care competence.
Neck Stabilization Exercises Enhance Respiratory Function after Stroke: Respiratory Function Index Change Trajectory Analyzed Using a Hierarchical Linear Model
Authors: Kim So-Hyun , Cho Sung-Hyoun
Published: November 2021

Background and Objectives: This study aimed to assess the effect of neck stabilization exercise on respiratory function in stroke patients through longitudinal observation and determine whether there is a difference in its effect based on the side of paralysis in the patients. It is difficult to observe the amount of change observed in individuals and groups as most intergroup comparison studies only use mean values. To address these shortcomings, this study adopted a hierarchical linear model (HLM) in our trajectory analysis. Materials and Methods: We conducted neck stabilization training three times a week for four weeks in a single group of 21 stroke patients. To evaluate respiratory function, their forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), forced expiration ratio (FEV1/FVC), and peak cough flow (PCF) were measured. Data analysis was performed using HLM 8.0. Results: A significant increase was found in the respiratory function after neck stabilization training (p < 0.05). While neck stabilization training overall was longitudinally effective, the growth rate of respiratory function in left-sided paralytic patients was less than the whole group value. Conversely, the growth rate of respiratory function in right-sided paralytic patients was greater than the whole group value. Conclusions: This study demonstrated that neck stabilization training is longitudinally effective in improving respiratory function in stroke patients. Additionally, the growth rate of respiratory function was greater in patients with right side paralysis than in patients with left side paralysis.
Mortality of Patients Infected by COVID-19 with and without Deep-Vein Thrombosis
Authors: Pereira de Godoy Jose Maria , Russeff Gleison Juliano da Silva , Costa Carolina Hungaro , Sato Debora Yuri , Silva Desirée Franccini Del Frari , Guerreiro Godoy Maria de Fatima , Pereira de Godoy Henrique Jose , Espada Paulo César
Published: November 2021

Background: Current evidence points to a state of hypercoagulability (consequence of hyperinflammation) as an important pathogenic mechanism that contributes to the increase in mortality in cases of COVID-19. The aim of the present study was to investigate the influence of deep-vein thrombosis on mortality patient’s infected with SARS-CoV-2. Method: A clinical trial was conducted involving 200 consecutive patients with COVID-19—100 patients who were positive for deep-vein thrombosis (venous Doppler ultrasound) and 100 who were negative for deep-vein thrombosis at a public hospital. Results: The mortality rate was 67% in the group positive for DVT and 31% in the group negative for DVT. Conclusion: Deep-vein thrombosis is associated with an increase in mortality in patients with COVID-19 and failures can occur with conventional prophylaxis for deep-vein thrombosis.
Electrospun Antibacterial Nanomaterials for Wound Dressings Applications
Authors: Gul Aysegul , Gallus Izabela , Tegginamath Akshat , Maryska Jiri , Yalcinkaya Fatma
Published: November 2021

Chronic wounds are caused by bacterial infections and create major healthcare discomforts; to overcome this issue, wound dressings with antibacterial properties are to be utilized. The requirements of antibacterial wound dressings cannot be fulfilled by traditional wound dressing materials. Hence, to improve and accelerate the process of wound healing, an antibacterial wound dressing is to be designed. Electrospun nanofibers offer a promising solution to the management of wound healing, and numerous options are available to load antibacterial compounds onto the nanofiber webs. This review gives us an overview of some recent advances of electrospun antibacterial nanomaterials used in wound dressings. First, we provide a brief overview of the electrospinning process of nanofibers in wound healing and later discuss electrospun fibers that have incorporated various antimicrobial agents to be used in wound dressings. In addition, we highlight the latest research and patents related to electrospun nanofibers in wound dressing. This review also aims to concentrate on the importance of nanofibers for wound dressing applications and discuss functionalized antibacterial nanofibers in wound dressing.
Synthetic Cell as a Platform for Understanding Membrane-Membrane Interactions
Authors: Sharma Bineet , Moghimianavval Hossein , Hwang Sung-Won , Liu Allen P.
Published: November 2021

In the pursuit of understanding life, model membranes made of phospholipids were envisaged decades ago as a platform for the bottom-up study of biological processes. Micron-sized lipid vesicles have gained great acceptance as their bilayer membrane resembles the natural cell membrane. Important biological events involving membranes, such as membrane protein insertion, membrane fusion, and intercellular communication, will be highlighted in this review with recent research updates. We will first review different lipid bilayer platforms used for incorporation of integral membrane proteins and challenges associated with their functional reconstitution. We next discuss different methods for reconstitution of membrane fusion and compare their fusion efficiency. Lastly, we will highlight the importance and challenges of intercellular communication between synthetic cells and synthetic cells-to-natural cells. We will summarize the review by highlighting the challenges and opportunities associated with studying membrane–membrane interactions and possible future research directions.
Comparative Study on Water Vapour Resistance of Poly(lactic acid) Films Prepared by Blending, Filling and Surface Deposit
Authors: Wang Shuo , Shen Qinyu , Guo Chuanyan , Guo Hongge
Published: November 2021

The polylactic acid (PLA) resin Ingeo 4032D was selected as the research object, with a focus on PLA modification by using polymers such as linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE) and ethylene–propylene-diene monomer grafted with glycidyl methacrylate (EPDM-g-GMA), by using fillers such as nano calcium carbonate and zeolite. In order to characterize the deposition effect of Al2O3 on the film surface by plasma-assisted atomic layer deposition, Bio-oriented PLA (BOPLA) with more uniform thickness than blown film was purchased for study. The mechanical properties, friction coefficient, surface contact angle and water vapour transmission rate of the modified PLA film were compared and discussed. The aim was to find out the most influencing factors of film’s water vapour resistance.
The Limitations in Current Studies of Organic Fouling and Future Prospects
Authors: Meng Xianghao , Meng Shujuan , Liu Yu
Published: November 2021

Microfiltration and ultrafiltration for water/wastewater treatment have gained global attention due to their high separation efficiency, while membrane fouling still remains one of their bottlenecks. In such a situation, many researchers attempt to obtain a deep understanding of fouling mechanisms and to develop effective fouling controls. Therefore, this article intends to trigger discussions on the appropriate choice of foulant surrogates and the application of mathematic models to analyze fouling mechanisms in these filtration processes. It has been found that the commonly used foulant surrogate (sodium alginate) cannot ideally represent the organic foulants in practical feed water to explore the fouling mechanisms. More surrogate foulants or extracellular polymeric substance (EPS) extracted from practical source water may be more suitable for use in the studies of membrane fouling problems. On the other hand, the support vector machine (SVM) which focuses on the general trends of filtration data may work as a more powerful simulation tool than traditional empirical models to predict complex filtration behaviors. Careful selection of foulant surrogate substances and the application of accurate mathematical modeling for fouling mechanisms would provide deep insights into the fouling problems.
Fabrication of Polysulfone-Surface Functionalized Mesoporous Silica Nanocomposite Membranes for Removal of Heavy Metal Ions from Wastewater
Authors: Alotaibi Abdullah A. , Shukla Arun Kumar , Mrad Mohamed Habib , Alswieleh Abdullah M. , Alotaibi Khalid M.
Published: November 2021

Membranes are an efficient way to treat emulsified heavy metal-based wastewater, but they generally come with a trade-off between permeability and selectivity. In this research, the amine and sulphonic groups on the inner and outer surface of mesoporous silica nanoparticles (MSNs) were first modified by a chemical approach. Then, MSNs with amine and sulphonic groups were utilized as new inorganic nanofiller to fabricate mixed matrix polysulfone (PSU) nanocomposite membranes using the classical phase inversion approach. The resultant nanoparticles and membranes were characterized by their physico-chemical characteristics as well as determination of pure water permeability along with cadmium and zinc ion removal. Embedding nanoparticles resulted in a significant rise in the water permeability as a result of changes in the surface properties and porosity of the membrane. Furthermore, the efficiency of developed membranes to remove cadmium and zinc was significantly improved by more than 90% due to the presence of functional groups on nanoparticles. The functionalized-MSNs/PSU nanocomposite membrane has the potential to be an effective industrial effluent removal membrane.
Upgrading Biogas from Small Agricultural Sources into Biomethane by Membrane Separation
Authors: Janusz-Cygan Aleksandra , Jaschik Jolanta , Tańczyk Marek
Published: November 2021

The agriculture sector in Poland could provide 7.8 billion m3 of biogas per year, but this potential would be from dispersed plants of a low capacity. In the current study, a membrane process was investigated for the upgrading biogas to biomethane that conforms to the requirements for grid gas in Poland. It was assumed that such a process is based on membranes made from modified polysulfone or polyimide, available in the market in Air Products PRISM PA1020 and UBE UMS-A5 modules, respectively. The case study has served an agricultural biogas plant in southern Poland, which provides the stream of 5 m3 (STP) h−1 of biogas with a composition of CH4 (52 vol.%), CO2 (46.3 vol.%), N2 (1.6 vol.%) and O2 (0.1 vol.%), after a pretreatment. It was theoretically shown that this is possible to obtain the biomethane stream of at least 96 vol.% of CH4 purity, with the concentration of the other biogas components below their respective thresholds, as required in Poland for gas fuel “E”, with methane recovery of up to 87.5% and 71.6% for polyimide and polysulfone membranes, respectively. The energetic efficiency of the separation process is comparable for both membrane materials, as expressed by power excess index, which reaches up to 51.3 kWth kWel−1 (polyimide) and 40.7 kWth kWel−1 (polysulfone). In turn, the membrane productivity was significantly higher in the case of the polyimide membrane (up to 38.3 kWth m−2) than those based on the polysulfone one (up to 3.13 kWth m−2).
Fundamentals of Membrane Lipid Replacement: A Natural Medicine Approach to Repairing Cellular Membranes and Reducing Fatigue, Pain, and Other Symptoms While Restoring Function in Chronic Illnesses and Aging
Authors: Nicolson Garth L. , Ferreira de Mattos Gonzalo , Ash Michael , Settineri Robert , Escribá Pablo V.
Published: November 2021

Membrane Lipid Replacement (MLR) uses natural membrane lipid supplements to safely replace damaged, oxidized lipids in membranes in order to restore membrane function, decrease symptoms and improve health. Oral MLR supplements contain mixtures of cell membrane glycerolphospholipids, fatty acids, and other lipids, and can be used to replace and remove damaged cellular and intracellular membrane lipids. Membrane injury, caused mainly by oxidative damage, occurs in essentially all chronic and acute medical conditions, including cancer and degenerative diseases, and in normal processes, such as aging and development. After ingestion, the protected MLR glycerolphospholipids and other lipids are dispersed, absorbed, and internalized in the small intestines, where they can be partitioned into circulating lipoproteins, globules, liposomes, micelles, membranes, and other carriers and transported in the lymphatics and blood circulation to tissues and cellular sites where they are taken in by cells and partitioned into various cellular membranes. Once inside cells, the glycerolphospholipids and other lipids are transferred to various intracellular membranes by lipid carriers, globules, liposomes, chylomicrons, or by direct membrane–membrane interactions. The entire process appears to be driven by ‘bulk flow’ or mass action principles, where surplus concentrations of replacement lipids can stimulate the natural exchange and removal of damaged membrane lipids while the replacement lipids undergo further enzymatic alterations. Clinical studies have demonstrated the advantages of MLR in restoring membrane and organelle function and reducing fatigue, pain, and other symptoms in chronic illness and aging patients.
Influence of Quenching and Partitioning Parameters on Phase Transformations and Mechanical Properties of Medium Manganese Steel for Press-Hardening Application
Authors: Blankart Charline , Wesselmecking Sebastian , Krupp Ulrich
Published: November 2021

It has been proven that through targeted quenching and partitioning (Q & P), medium manganese steels can exhibit excellent mechanical properties combining very high strength and ductility. In order to apply the potential of these steels in industrial press hardening and to avoid high scrap rates, it is of utmost importance to determine a robust process window for Q & P. Hence, an intensive study of dilatometry experiments was carried out to identify the influence of quenching temperature (TQ) and partitioning time (tp) on phase transformations, phase stabilities, and the mechanical properties of a lean medium manganese steel. For this purpose, additional scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and energy dispersive X-ray spectroscopy (EDX) examinations as well as tensile testing were performed. Based on the dilatometry data, an adjustment of the Koistinen–Marburger (K-M) equation for medium manganese steel was developed. The results show that a retained austenite content of 12–21% in combination with a low-phase fraction of untempered secondary martensite (max. 20%) leads to excellent mechanical properties with a tensile strength higher than 1500 MPa and a total elongation of 18%, whereas an exceeding secondary martensite phase fraction results in brittle failure. The optimum retained austenite content was adjusted for TQ between 130 °C and 150 °C by means of an adapted partitioning.
Deformation Behavior of Wrought and EBAM Ti-6Al-4V under Scratch Testing
Authors: Shugurov Artur , Panin Alexey , Kazachenok Marina , Kazantseva Lyudmila , Martynov Sergey , Bakulin Alexander , Kulkova Svetlana
Published: November 2021

The microstructure, mechanical properties, and deformation behavior of wrought and electron beam additive manufactured (EBAM) Ti-6Al-4V samples under scratching were studied. As-received wrought Ti-6Al-4V was subjected to thermal treatment to obtain the samples with microstructure and mechanical characteristics similar to those of the EBAM samples. As a result, both alloys consisted of colonies of α phase laths within prior β phase grains and were characterized by close values of hardness. At the same time, the Young’s modulus of the EBAM samples determined by nanoindentation was lower compared with the wrought samples. It was found that despite the same hardness, the scratch depth of the EBAM samples under loading was substantially smaller than that of the wrought alloy. A mechanism was proposed, which associated the smaller scratch depth of EBAM Ti-6Al-4V with α′→α″ phase transformations that occurred in the contact area during scratching. Ab initio calculations of the atomic structure of V-doped Ti crystallites containing α or α″ phases of titanium were carried out to support the proposed mechanism.
Selective Laser Melting of High Relative Density and High Strength Parts Made of Minor Surface Oxidation Treated Pure Copper Powder
Authors: Yang Peng , Guo Xingye , He Dingyong , Tan Zhen , Shao Wei , Fu Hanguang
Published: November 2021

Pure Copper (Cu) is very difficult to prepare using selective laser melting (SLM) technology. This work successfully prepared the pure Cu with high relative density and high strength by the SLM technology using a surface oxidation treatment. The gas-atomized pure Cu powder was used as the feedstock in this work. Before the SLM process, the pure Cu powder was initially handled using the surface oxidation treatment to coat the powder with an extremely thin layer of Cu2O. The SLMed highly dense specimens contain α-Cu and nano-Cu2O phases. A relationship between the processing parameters (laser power (LP), scanning speed (SS), and hatch space (HS)) and density of Cu alloy in SLM was also investigated. The microstructure of SLMed Cu consists of fine grains with grain sizes ranging from 0.5 to ~30 μm. Tensile testing and detailed microstructural characterization were performed on specimens in the as-SLMed and pure copper state specimens. The mechanical property experiments showed that the specimens prepared by SLM technology containing nano-oxide phases had higher yield strength and tensile strength than that of other SLM-built pure copper. However, the elongation was remarkably decreased compared to other SLM-built pure copper, due to the fine grains and the nano-oxides.
Phase Transitions in the Co–Al–Nb–Mo System
Authors: Davydov Denis , Kazantseva Nataliya , Popov Nikolai , Vinogradova Nina , Ezhov Igor
Published: November 2021

Phase transitions in the Co-rich part of the Co–Al–Nb–Mo phase diagram are studied by energy dispersive spectroscopy (EDS), X-ray analysis, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) measurements. The obtained results were compared with the results for alloys of the binary Co–Al and ternary Co–Al–Nb, and Co–Al–Mo systems. Formation of the intermetallic phase with the L12 structure was found in a range of alloys with 10 at.% Al, 2–9 at.% Nb, and 3–7 at.% Mo. Intermetallic compound Co2Nb, Laves phase with the different chemical composition and crystal structure (C14 and C36) was detected in the Co–Al–Nb and Co–Al–Nb–Mo samples after vacuum solution treating at 1250 °C for 30 h.
Characterization and Analysis of Nanocrystalline Soft Magnetic Alloys: Fe Based
Authors: Daza Jason , Ben Mbarek Wael , Escoda Lluisa , Suñol Joan-Josep
Published: November 2021

Soft magnetic nanocrystalline alloys have been widely analysed and studied during the past years. However, optimisation of specific chemical compositions is still being developed. The applicability of these soft nanocrystalline alloys depends mainly on the presence of the desired nanocrystalline phases within the alloy. In this study, the analysed alloys are manufactured by mechanical alloying. The analyses performed on the samples include a microstructural analysis, a thermal analysis, and a complementary functional analysis in the form of the thermomagnetic response of some samples. Regarding Fe-based alloys, thermal stability for samples containing B was higher than those containing P (crystal growth peaks in the range between 895–905 K and 775–800 K respectively). The higher magnetization of saturation, Ms, was found in Fe–Mn alloys, whereas the addition of boron provoked a decrease of Ms and the nanocrystals size.
Effects of La on Thermal Stability, Phase Formation and Magnetic Properties of Fe–Co–Ni–Si–B–La High Entropy Alloys
Authors: Li Jiaming , Zuo Jianliang , Yu Hongya
Published: November 2021

The microstructure, phase formation, thermal stability and soft magnetic properties of melt-spun high entropy alloys (HEAs) Fe27Co27Ni27Si10−xB9Lax with various La substitutions for Si (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) were investigated in this work. The Fe27Co27Ni27Si10−xB9La0.6 alloy shows superior soft magnetic properties with low coercivity Hc of ~7.1 A/m and high saturation magnetization Bs of 1.07 T. The content of La has an important effect on the primary crystallization temperature (Tx1) and the secondary crystallization temperature (Tx2) of the alloys. After annealing at relatively low temperature, the saturation magnetization of the alloy increases and the microstructure with a small amount of body-centered cubic (BCC) phase embedded in amorphous matrix is observed. Increasing the annealing temperature reduces the magnetization due to the transformation of BCC phase into face-centered cubic (FCC) phase.