bluuebunny/crossref_metadata_2025 huggingface dataset:
Methylenealkane-Based Low-Viscosity Ester Oils: Synthesis and Outlook
Authors: Nifant’ev Ilya , Bagrov Vladimir , Vinogradov Alexander , Vinogradov Alexey , Ilyin Sergey , Sevostyanova Nadezhda , Batashev Sergey , Ivchenko Pavel
Published: May 2020

Both Group 4 poly-α-olefin (PAO) and Group 5 ester oil basestocks are used in formulations of synthetic engine oils, transmission fluids, and lubricants with leading characteristics such as low viscosity (providing fuel saving), high stability, and environmental safety. The modern technologies of the production of PAOs use catalytic oligomerization of α-olefins, which is complicated by the formation of low-molecular-weight α-olefin dimers (methylenealkanes) as imminent side products. The use of methylenealkanes as raw materials for the synthesis of Group 5 base stocks appears to be highly promising. In the present work, we report the use of methyl 3-butylnonanoate and methyl 3-hexylundecanoate, the products of catalytic methoxycarbonylation of hex-1-ene and oct-1-ene dimers, in the synthesis of two series of branched isomeric esters. These esters demonstrated excellent rheological behavior and may be considered as low-viscosity engine oils with leading characteristics.
Planar-Chiral P and N-bridged Diferrocenes
Authors: Honegger Philipp , Scheibelberger Lukas , Widhalm Michael
Published: May 2020

We describe the synthesis of planar-chiral diferrocene compounds 4, 7 and 12, intended as key precursors for a new family of asymmetric catalyst ligands with less complex structures than their popular equivalents. In contrast to conventional 1,2-disubstituted ferrocenes containing center-chiral and planar-chiral elements, these compounds are purely planar-chiral due to the absence of α-substiuted ethyl groups. The title compounds 4, 7 and 12 were obtained from known precursors in 87%, 59% and 60% yields, respectively.
Si–Fe–C–N Coatings for Biomedical Applications: A Combinatorial Approach
Authors: Skjöldebrand Charlotte , Hulsart-Billström Gry , Engqvist Håkan , Persson Cecilia
Published: May 2020

Ceramic coatings may prolong the lifetime of joint implants. Certain ions and wear debris may however lead to negative biological effects. SiN-based materials may substantially reduce these effects, but still need optimization for the application. In this study, a combinatorial deposition method enabled an efficient evaluation of a range of Si–Fe–C–N coating compositions on the same sample. The results revealed compositional gradients of Si (26.0–33.9 at.%), Fe (9.6–20.9 at.%), C (8.2–13.9 at.%) and N (39.7–47.2 at.%), and low oxygen contaminations (0.3–0.6 at.%). The mechanical properties varied with a hardness (H) ranging between 13.7–17.3 GPa and an indentation modulus (M) between 190–212 GPa. Both H and M correlated with the Si (H and M increased as Si increased) and Fe (H and M decreased as Fe increased) content. A slightly columnar morphology was observed in cross-sections, as well as a surface roughness in the nm range. A cell study revealed adhering pre-osteogenic MC3T3 cells, with a morphology similar to that of cells seeded on a tissue culture plastic control. The investigated coatings could be considered for further investigation due to the ability to tune their mechanical properties while maintaining a smooth surface, together with their promising in vitro cell response.
Experimental Studies of Concrete-Filled Composite Tubes under Axial Short- and Long-Term Loads
Authors: Abramski Marcin , Korzeniowski Piotr , Klempka Krzysztof
Published: May 2020

The paper presents experimental studies on axially compressed columns made of concrete-filled glass fiber reinforced polymer (GFRP) tubes. The infill concrete was C30/37 according to Eurocode 2. The investigated composite pipes were characterized by different angles of fiber winding in relation to the longitudinal axis of the element: 20, 55 and 85 degrees. Columns of two lengths, 0.4 m and 2.0 m, were studied. The internal diameter and wall thickness of all the pipes were identical and amounted to 200 mm and 6 mm, respectively. The mean values of two mechanical properties, elasticity modulus and compression strength, were determined. These properties were determined for longitudinal compression and for circumferential tension. The graphs of longitudinal and peripheral deformations of polymer shells as a function of load level are presented both for empty tubes and for concrete-filled ones. The results of long-term investigations of three identically made 0.4 m high concrete-filled GFRP tubes are also presented.
High Potential of Bacterial Adhesion on Block Bone Graft Materials
Authors: Nisyrios Themistoklis , Karygianni Lamprini , Fretwurst Tobias , Nelson Katja , Hellwig Elmar , Schmelzeisen Rainer , Al-Ahmad Ali
Published: May 2020

Bone graft infections represent a challenge in daily clinics, resulting in increased patient discomfort and graft removal. The aim of this study was to investigate the initial adhesion of five representative pathogens on three different block bone graft materials (xenogeneic, alloplastic and allogeneic) and to assess if chlorhexidine (CHX) can effectively control the initial bacterial adhesion. Three different block bone grafting materials (Tutobone®, Endobon® and human spongiosa) were incubated with Escherichia coli, Staphylococcus aureus, Streptococcus mutans, Enterococcus faecalis and Pseudomonas aeruginosa in the presence or absence of 0.2% CHX solution. Bacterial adhesion was assessed by the direct counting of the colony-forming units (CFUs) and visualized by scanning electron microscopy (SEM). Overall, the selected bacterial species adhered successfully to all tested bone replacement scaffolds, which showed similar bacterial counts. The lg CFU values ranged from 5.29 ± 0.14 to 5.48 ± 0.72 for E. coli, from 4.37 ± 0.62 to 5.02 ± 0.48 for S. aureus, from 4.92 ± 0.34 to 4.95 ± 0.21 for S. mutans, from 4.97 ± 0.40 to 5.22 ± 0.13 for E. faecalis and from 4.23 ± 0.54 to 4.58 ± 0.26 for P. aeruginosa. CHX did not interfere with initial microbial adhesion, and yet it killed all adhered bacterial cells. Thus, CHX can be used to prevent subsequent biofilm infections.
Additively Manufactured NiTi and NiTiHf Alloys: Estimating Service Life in High-Temperature Oxidation
Authors: Dabbaghi Hediyeh , Safaei Keyvan , Nematollahi Mohammadreza , Bayati Parisa , Elahinia Mohammad
Published: May 2020

In this study, the effect of the addition of Hf on the oxidation behavior of NiTi alloy, which was processed using additive manufacturing and casting, is studied. Thermogravimetric analyses (TGA) were performed at the temperature of 500, 800, and 900 °C to assess the isothermal and dynamic oxidation behavior of the Ni50.4Ti29.6Hf20 at.% alloys for 75 h in dry air. After oxidation, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to analyze the oxide scale formed on the surface of the samples during the high-temperature oxidation. Two stages of oxidation were observed for the NiTiHf samples, an increasing oxidation rate during the early stage of oxidation followed by a lower oxidation rate after approximately 10 h. The isothermal oxidation curves were well matched with a logarithmic rate law in the initial stage and then by parabolic rate law for the next stage. The formation of multi-layered oxide was observed for NiTiHf, which consists of Ti oxide, Hf oxide, and NiTiO3. For the binary alloys, results show that by increasing the temperature, the oxidation rate increased significantly and fitted with parabolic rate law. Activation energy of 175.25 kJ/mol for additively manufactured (AM) NiTi and 60.634 kJ/mol for AM NiTiHf was obtained.
Investigation of the Influence of PLA Molecular and Supramolecular Structure on the Kinetics of Thermal-Supported Hydrolytic Degradation of Wet Spinning Fibres
Authors: Giełdowska Małgorzata , Puchalski Michał , Szparaga Grzegorz , Krucińska Izabella
Published: May 2020

In this study, differences in the kinetics of the thermal-supported hydrolytic degradation of polylactide (PLA) wet spinning fibres due to material variance in the initial molecular and supramolecular structure were analysed. The investigation was carried out at the microstructural and molecular levels by using readily available methods such as scanning electron microscopy, mass erosion measurement and estimation of intrinsic viscosity. The results show a varying degree of influence of the initial structure on the degradation rate of the studied PLA fibres. The experiment shows that hydrolytic degradation at a temperature close to the cold crystallization temperature is, on a macroscopic level, definitely more rapid for the amorphous material, while on a molecular scale it is similar to a semi-crystalline material. Furthermore, for the adopted degradation temperature of 90 °C, a marginal influence of the pH of the degradation medium on the degradation kinetics was also demonstrated.
Improving the Blast Resistance of Large Steel Gates—Numerical Study
Authors: Al-Rifaie Hasan , Sumelka Wojciech
Published: May 2020

Blast resistant gates/doors are essential for sensitive infrastructure, such as embassies, ministries, or parliaments. Lightweight gates equipped with ‘energy absorbing systems’ have better operational performance than the traditional costly and bulky design. Graded auxetic structures have not yet been used as potential passive damping systems in the supporting frame of blast resistant gates. Consequently, this study tries to test if a uniaxial graded auxetic damper (UGAD) proposed by the authors in a recent article, namely the development of a new shock absorbing UGAD, could maintain a 3000 mm × 4500 mm steel gate operable after high blast peak reflected overpressure of 6.6 MPa, from 100 kg TNT at 5 m stand-off distance. The blast-induced response of the gate was assessed, with and without the proposed UGAD, using Abaqus/Explicit solver. Results showed that the attachment of the proposed UGAD to the gate led to a dramatic decrease in permanent deformations (a critical factor for gate operability after a blast event). Hence, a lighter, more economical gate (with 50% reduction in mass) was required to satisfy the operability condition. In addition, 49% of peak reaction forces were diminished, that have a direct impact on the supporting frame. Moreover, the results revealed that, in the numerical model, 56% of the achieved plastic dissipation energy was from the UGADs, and 44% from the gate. The outcomes of this research may have a positive impact on other sectors beyond academia, such as industry, economy, and public safety.
The Effect of Ball Burnishing on Tribological Performance of 42CrMo4 Steel under Dry Sliding Conditions
Authors: Swirad Slawomir , Pawlus Pawel
Published: May 2020

Ball burnishing appears to be a very promising approach for reducing surface height, generating compressive residual stresses and increasing hardness. Ball burnishing treatment was carried out using a Haas CNC Vertical Mill Center VF-1 equipped with the Ecoroll burnishing system. After burnishing, surface topographies of machined samples and hardness were measured. Wear tests were conducted using a ball-on-disc tribotester in dry sliding conditions. During tests, the friction force was monitored as a function of time. After tests, wear volumes were determined on the basis of surface texture measurements. Tests revealed that ball burnishing in most cases resulted in minimizing friction and wear of contacting elements.
Hot Corrosion and Mechanical Performance of Repaired Inconel 718 Components via Laser Additive Manufacturing
Authors: Zhang Qunli , Zhang Jie , Zhuang Yifan , Lu Jinzhong , Yao Jianhua
Published: May 2020

Hot corrosion is one of the crucial failure modes of Ni-based superalloy components operating at high temperatures, which inevitably affects the subsequent mechanical properties of the alloys. In this research, damaged Inconel 718 alloy components with a pre-made trapezoid groove are repaired using laser additive manufacturing technique, and the change mechanisms of the microstructure and tensile properties of the repaired Inconel 718 alloy due to the hot corrosion in the salt mixture of 87.5 wt.% Na2SO4 + 5 wt.% NaCl + 7.5 wt.% NaNO3 at 650 °C for different durations are investigated. The results show that oxidation and Cr-depletion occur on the repaired components due to the hot corrosion, and the corrosion products are mainly composed of Cr2O3, Fe3O4, and Ni3S2. The tensile strength and elongation of the as-repaired specimens are 736.6 MPa and 12.5%, respectively. After being hot corroded for 50 h, the tensile strength increases to 1022.9 MPa and elongation decreases to 1.7%. However, after being hot corroded for 150 h, both tensile strength and elongation of the repaired specimens drop to 955.8 MPa and 1.2%, respectively. The mechanical performance alteration is highly related to thermal effects instead of the molten salt attack.
Studying Bone Remodelling and Tumour Growth for Therapy Predictive Control
Authors: Miranda Raquel , Vinga Susana , Valério Duarte
Published: May 2020

Bone remodelling consists of cycles of bone resorption and formation executed mainly by osteoclasts and osteoblasts. Healthy bone remodelling is disrupted by diseases such as Multiple Myeloma and bone metastatic diseases. In this paper, a simple mathematical model with differential equations, which takes into account the evolution of osteoclasts, osteoblasts, bone mass and bone metastasis growth, is improved with a pharmacokinetic and pharmacodynamic (PK/PD) scheme of the drugs denosumab, bisphosphonates, proteasome inhibitors and paclitaxel. The major novelty is the inclusion of drug resistance phenomena, which resulted in two variations of the model, corresponding to different paradigms of the origin and development of the tumourous cell resistance condition. These models are then used as basis for an optimization of the drug dose applied, paving the way for personalized medicine. A Nonlinear Model Predictive Control scheme is used, which takes advantage of the convenient properties of a suggested adaptive and democratic variant of Particle Swarm Optimization. Drug prescriptions obtained in this way provide useful insights into dose administration strategies. They also show how results may change depending on which of the two very different paradigms of drug resistance is used to model the behaviour of the tumour.
Existence and Multiplicity Results for Nonlocal Boundary Value Problems with Strong Singularity
Authors: Kim Chan-Gyun
Published: May 2020

In this paper, we study singular φ -Laplacian nonlocal boundary value problems with a nonlinearity which does not satisfy the L 1 -Carathéodory condition. The existence, nonexistence and/or multiplicity results of positive solutions are established under two different asymptotic behaviors of the nonlinearity at ∞.
Innovative Platform for Designing Hybrid Collaborative & Context-Aware Data Mining Scenarios
Authors: Avram Anca , Matei Oliviu , Pintea Camelia , Anton Carmen
Published: May 2020

The process of knowledge discovery involves nowadays a major number of techniques. Context-Aware Data Mining (CADM) and Collaborative Data Mining (CDM) are some of the recent ones. the current research proposes a new hybrid and efficient tool to design prediction models called Scenarios Platform-Collaborative & Context-Aware Data Mining (SP-CCADM). Both CADM and CDM approaches are included in the new platform in a flexible manner; SP-CCADM allows the setting and testing of multiple configurable scenarios related to data mining at once. The introduced platform was successfully tested and validated on real life scenarios, providing better results than each standalone technique—CADM and CDM. Nevertheless, SP-CCADM was validated with various machine learning algorithms—k-Nearest Neighbour (k-NN), Deep Learning (DL), Gradient Boosted Trees (GBT) and Decision Trees (DT). SP-CCADM makes a step forward when confronting complex data, properly approaching data contexts and collaboration between data. Numerical experiments and statistics illustrate in detail the potential of the proposed platform.
Attribute Reduction in Soft Contexts Based on Soft Sets and Its Application to Formal Contexts
Authors: Min Won Keun
Published: May 2020

We introduce the notion of the reduct of soft contexts, which is a special notion of a consistent set for soft contexts. Then, we study its properties and show that this notion is well explained by the two classes, 1 0 and 2 0 , of independent attributes. In particular, we describe in detail how to extract a reduct from a given consistent set. Then, based on this extraction process, we propose a six-step method for constructing a reduct from a given consistent set. Additionally, to apply this method to formal contexts, we examine the relationship between the reducts of a given formal context and the reducts of the associated soft context. We finally illustrate the process of obtaining reducts in a formal context using this relationship and the six-step method using an example.
An Adaptive Image Watermarking Method Combining SVD and Wang-Landau Sampling in DWT Domain
Authors: Wang Baowei , Zhao Peng
Published: May 2020

To keep a better trade-off between robustness and imperceptibility is difficult for traditional digital watermarks. Therefore, an adaptive image watermarking method combining singular value decomposition (SVD) and the Wang–Landau (WL) sampling method is proposed to solve the problem. In this method, the third-level approximate sub-band obtained by applying the three-level wavelet transform is decomposed by SVD to obtain the principal component, which is firstly selected as the embedded position. Then, the information is finally embedded into the host image by the scaling factor. The Wang–Landau sampling method is devoted to finding the best embedding coefficient through the proposed objective evaluation function, which is a global optimization algorithm. The embedding strength is adaptively adjusted by utilizing the historical experience, which overcomes the problem of falling into local optimization easily in many traditional optimization algorithms. To affirm the reliability of the proposed method, several image processing attacks are applied and the experimental results are given in detail. Compared with other existing related watermarking techniques based on both qualitative and quantitative evaluation parameters, such as peak signal to noise ratio (PSNR) and normalized cross-correlation (NC), this method has been proven to achieve a trade-off between robustness and invisibility.
Double Fuzzy Sumudu Transform to Solve Partial Volterra Fuzzy Integro-Differential Equations
Authors: Georgieva Atanaska
Published: May 2020

In this paper, the double fuzzy Sumudu transform (DFST) method was used to find the solution to partial Volterra fuzzy integro-differential equations (PVFIDE) with convolution kernel under Hukuhara differentiability. Fundamental results of the double fuzzy Sumudu transform for double fuzzy convolution and fuzzy partial derivatives of the n-th order are provided. By using these results the solution of PVFIDE is constructed. It is shown that DFST method is a simple and reliable approach for solving such equations analytically. Finally, the method is demonstrated with examples to show the capability of the proposed method.
An Extension of the Concept of Derivative: Its Application to Intertemporal Choice
Authors: Cruz Rambaud Salvador , Torrecillas Jover Blas
Published: May 2020

The framework of this paper is the concept of derivative from the point of view of abstract algebra and differential calculus. The objective of this paper is to introduce a novel concept of derivative which arises in certain economic problems, specifically in intertemporal choice when trying to characterize moderately and strongly decreasing impatience. To do this, we have employed the usual tools and magnitudes of financial mathematics with an algebraic nomenclature. The main contribution of this paper is twofold. On the one hand, we have proposed a novel framework and a different approach to the concept of relative derivation which satisfies the so-called generalized Leibniz’s rule. On the other hand, in spite of the fact that this peculiar approach can be applied to other disciplines, we have presented the mathematical characterization of the two main types of decreasing impatience in the ambit of behavioral finance, based on a previous characterization involving the proportional increasing of the variable “time”. Finally, this paper points out other patterns of variation which could be applied in economics and other scientific disciplines.
The Curve Shortening Flow in the Metric-Affine Plane
Authors: Rovenski Vladimir
Published: May 2020

We investigated, for the first time, the curve shortening flow in the metric-affine plane and prove that under simple geometric condition (when the curvature of initial curve dominates the torsion term) it shrinks a closed convex curve to a “round point” in finite time. This generalizes the classical result by M. Gage and R.S. Hamilton about convex curves in a Euclidean plane.
On Phase-I Monitoring of Process Location Parameter with Auxiliary Information-Based Median Control Charts
Authors: Hussain Shahid , Mei Sun , Riaz Muhammad , Abbasi Saddam Akber
Published: May 2020

A control chart is often used to monitor the industrial or services processes to improve the quality of the products. Mostly, the monitoring of location parameters, both in Phase I and Phase II, is done using a mean control chart with the assumption that the process is free from outliers or the estimators are correctly estimated from in-control samples. Generally, there are question marks about such kind of narratives. The performance of the mean chart is highly affected in the presence of outliers. Therefore, the median chart is an attractive alternative to the mean chart in this situation. The control charts are usually implemented in two phases: Phase I (retrospective) and Phase II (prospective/monitoring). The efficiency of any control chart in Phase II depends on the accuracy of control limits obtained from Phase I. The current study focuses on the Phase I analysis of location parameters using median control charts. We examined the performance of different auxiliary information-based median control charts and compared the results with the usual median chart. Standardized variance and relative efficacy are used as performance measures to evaluate the efficiency of median estimators. Moreover, the probability to signal measure is used to evaluate the performance of proposed control charts to detect any potential changes in the process. The results revealed that the proposed auxiliary information based median control charts perform better in Phase I analysis. In addition, a practical illustration of an industrial scenario demonstrated the significance of the proposed control charts, in which the monitoring of concrete compressive strength is emphasized.
M-CFIS-R: Mamdani Complex Fuzzy Inference System with Rule Reduction Using Complex Fuzzy Measures in Granular Computing
Authors: Tuan Tran Manh , Lan Luong Thi Hong , Chou Shuo-Yan , Ngan Tran Thi , Son Le Hoang , Giang Nguyen Long , Ali Mumtaz
Published: May 2020

Complex fuzzy theory has strong practical background in many important applications, especially in decision-making support systems. Recently, the Mamdani Complex Fuzzy Inference System (M-CFIS) has been introduced as an effective tool for handling events that are not restricted to only values of a given time point but also include all values within certain time intervals (i.e., the phase term). In such decision-making problems, the complex fuzzy theory allows us to observe both the amplitude and phase values of an event, thus resulting in better performance. However, one of the limitations of the existing M-CFIS is the rule base that may be redundant to a specific dataset. In order to handle the problem, we propose a new Mamdani Complex Fuzzy Inference System with Rule Reduction Using Complex Fuzzy Measures in Granular Computing called M-CFIS-R. Several fuzzy similarity measures such as Complex Fuzzy Cosine Similarity Measure (CFCSM), Complex Fuzzy Dice Similarity Measure (CFDSM), and Complex Fuzzy Jaccard Similarity Measure (CFJSM) together with their weighted versions are proposed. Those measures are integrated into the M-CFIS-R system by the idea of granular computing such that only important and dominant rules are being kept in the system. The difference and advantage of M-CFIS-R against M-CFIS is the usage of the training process in which the rule base is repeatedly changed toward the original base set until the performance is better. By doing so, the new rule base in M-CFIS-R would improve the performance of the whole system. Experiments on various decision-making datasets demonstrate that the proposed M-CFIS-R performs better than M-CFIS.
Parameter and Reliability Inferences of Inverted Exponentiated Half-Logistic Distribution under the Progressive First-Failure Censoring
Authors: Zhang Fengshi , Gui Wenhao
Published: May 2020

Using progressive first-failure censored samples, we mainly study the inferences of the unknown parameters and the reliability and failure functions of the Inverted Exponentiated Half-Logistic distribution. The progressive first-failure censoring is an extension and improvement of progressive censoring, which is of great significance in the field of lifetime research. Besides maximum likelihood estimation, we use Bayesian estimation under unbalanced and balanced losses: General Entropy loss function, Squared Error loss function and Linex loss function. Approximate explicit expression of Bayesian estimation is given using Lindley approximation method for point estimation and Metropolis-Hastings method for point and interval estimation. Bayesian credible intervals and asymptotic confidence intervals are derived in the form of average length and coverage probability. To show the research effects, a simulation study and practical data analysis are carried out. Finally, we discuss the optimal censoring mode under four different criteria.
Dominance-Based Decision Rules for Pension Fund Selection under Different Distributional Assumptions
Authors: Kabašinskas Audrius , Šutienė Kristina , Kopa Miloš , Lukšys Kęstutis , Bagdonas Kazimieras
Published: May 2020

The pension landscape is changing due to the market situation, and technological change has enabled financial innovations. Pension savers usually seek financial advice to make a personalised decision in selecting the right pension fund for them. As such, decision rules based on the assumed risk profile of the decision maker could be generated by making use of stochastic dominance (SD). In the paper, the second-pillar pension funds operating in Lithuania and Slovakia are analysed according to SD rules. The importance of the distributional assumption is explored while comparing the results of empirical, student-t, Hyperbolic and Normal Inverse Gaussian distributions to generate SD-based rules that could be integrated into an advisory solution. Moreover, due to the differences in SD results under different distributional assumptions, a new SD ratio is proposed that condenses the dominance-based relations for all considered dominance orders and probability distributions. The empirical results indicate that this new SD ratio efficiently characterises not only the preference of each fund individually but also of a group of funds with the same attributes, thus enabling multi-risk and multi-country comparisons.
Learning Algorithms for Coarsening Uncertainty Space and Applications to Multiscale Simulations
Authors: Zhang Zecheng , Chung Eric T. , Efendiev Yalchin , Leung Wing Tat
Published: May 2020

In this paper, we investigate and design multiscale simulations for stochastic multiscale PDEs. As for the space, we consider a coarse grid and a known multiscale method, the generalized multiscale finite element method (GMsFEM). In order to obtain a small dimensional representation of the solution in each coarse block, the uncertainty space needs to be partitioned (coarsened). This coarsenining collects realizations that provide similar multiscale features as outlined in GMsFEM (or other method of choice). This step is known to be computationally demanding as it requires many local solves and clustering based on them. In this work, we take a different approach and learn coarsening the uncertainty space. Our methods use deep learning techniques in identifying clusters (coarsening) in the uncertainty space. We use convolutional neural networks combined with some techniques in adversary neural networks. We define appropriate loss functions in the proposed neural networks, where the loss function is composed of several parts that includes terms related to clusters and reconstruction of basis functions. We present numerical results for channelized permeability fields in the examples of flows in porous media.
IDP-Core: Novel Cooperative Solution for Differential Games
Authors: Petrosian Ovanes , Zakharov Victor
Published: May 2020

IDP-core is a new cooperative solution for dynamic and differential games. A novel approach of constructing solutions for dynamic and differential games was employed in which the time consistency property was used as the main axiom property for the cooperative solution. Another new and important approach used for constructing IDP-core is the IDP dominance, which allows to select undominated imputation distribution procedures and construct the cooperative solution or imputation set. This approach shows the potential of using the time consistency property as the main axiom for solutions in various fields such as Social Choice and Mechanism Design. The overall procedure for defining the cooperative solution is also new since IDP-core was constructed using imputation distribution procedures but not by using imputations directly.
A Projection Hestenes–Stiefel Method with Spectral Parameter for Nonlinear Monotone Equations and Signal Processing
Authors: Awwal Aliyu Muhammed , Wang Lin , Kumam Poom , Mohammad Hassan , Watthayu Wiboonsak
Published: May 2020

A number of practical problems in science and engineering can be converted into a system of nonlinear equations and therefore, it is imperative to develop efficient methods for solving such equations. Due to their nice convergence properties and low storage requirements, conjugate gradient methods are considered among the most efficient for solving large-scale nonlinear equations. In this paper, a modified conjugate gradient method is proposed based on a projection technique and a suitable line search strategy. The proposed method is matrix-free and its sequence of search directions satisfies sufficient descent condition. Under the assumption that the underlying function is monotone and Lipschitzian continuous, the global convergence of the proposed method is established. The method is applied to solve some benchmark monotone nonlinear equations and also extended to solve ℓ 1 -norm regularized problems to reconstruct a sparse signal in compressive sensing. Numerical comparison with some existing methods shows that the proposed method is competitive, efficient and promising.
Monogalactosyldiacylglycerol and Sulfolipid Synthesis in Microalgae
Authors: Riccio Gennaro , De Luca Daniele , Lauritano Chiara
Published: May 2020

Microalgae, due to their huge taxonomic and metabolic diversity, have been shown to be a valuable and eco-friendly source of bioactive natural products. The increasing number of genomic and transcriptomic data will give a great boost for the study of metabolic pathways involved in the synthesis of bioactive compounds. In this study, we analyzed the presence of the enzymes involved in the synthesis of monogalactosyldiacylglycerols (MGDGs) and sulfoquinovosyldiacylglycerols (SQDG). Both compounds have important biological properties. MGDGs present both anti-inflammatory and anti-cancer activities while SQDGs present immunostimulatory activities and inhibit the enzyme glutaminyl cyclase, which is involved in Alzheimer’s disease. The Ocean Global Atlas (OGA) database and the Marine Microbial Eukaryotic Transcriptome Sequencing Project (MMETSP) were used to search MGDG synthase (MGD), UDP-sulfoquinovose synthase (SQD1), and sulfoquinovosyltransferase (SQD2) sequences along microalgal taxa. In silico 3D prediction analyses for the three enzymes were performed by Phyre2 server, while binding site predictions were performed by the COACH server. The analyzed enzymes are distributed across different taxa, which confirms the importance for microalgae of these two pathways for thylakoid physiology. MGD genes have been found across almost all analyzed taxa and can be separated in two different groups, similarly to terrestrial plant MGD. SQD1 and SQD2 genes are widely distributed along the analyzed taxa in a similar way to MGD genes with some exceptions. For Pinguiophyceae, Raphidophyceae, and Synurophyceae, only sequences coding for MGDG were found. On the contrary, sequences assigned to Ciliophora and Eustigmatophyceae were exclusively corresponding to SQD1 and SQD2. This study reports, for the first time, the presence/absence of these enzymes in available microalgal transcriptomes, which gives new insights on microalgal physiology and possible biotechnological applications for the production of bioactive lipids.
Bengamide Analogues Show A Potent Antitumor Activity against Colon Cancer Cells: A Preliminary Study
Authors: García-Pinel Beatriz , Porras-Alcalá Cristina , Cabeza Laura , Ortiz Raul , Prados José , Melguizo Consolación , Cheng-Sánchez Iván , López-Romero Juan Manuel , Sarabia Francisco
Published: May 2020

The limited success and side effects of the current chemotherapeutic strategies against colorectal cancer (CRC), the third most common cancer worldwide, demand an assay with new drugs. The prominent antitumor activities displayed by the bengamides (Ben), a family of natural products isolated from marine sponges of the Jaspidae family, were explored and investigated as a new option to improve CRC treatment. To this end, two potent bengamide analogues, Ben I (5) and Ben V (10), were selected for this study, for which they were synthesized according to a new synthetic strategy recently developed in our laboratories. Their antitumor effects were analyzed in human and mouse colon cell lines, using cell cycle analysis and antiproliferative assays. In addition, the toxicity of the selected analogues was tested in human blood cells. These biological studies revealed that Ben I and V produced a significant decrease in CRC cell proliferation and induced a significant cell cycle alteration with a greater antiproliferative effect on tumor cell lines than normal cells. Interestingly, no toxicity effects were detected in blood cells for both compounds. All these biological results render the bengamide analogues Ben I and Ben V as promising antitumoral agents for the treatment of CRC.
Membrane Technologies in Wastewater Treatment: A Review
Authors: Obotey Ezugbe Elorm , Rathilal Sudesh
Published: May 2020

In the face of water shortages, the world seeks to explore all available options in reducing the over exploitation of limited freshwater resources. One of the surest available water resources is wastewater. As the population grows, industrial, agricultural, and domestic activities increase accordingly in order to cater for the voluminous needs of man. These activities produce large volumes of wastewater from which water can be reclaimed to serve many purposes. Over the years, conventional wastewater treatment processes have succeeded to some extent in treating effluents for discharge purposes. However, improvements in wastewater treatment processes are necessary in order to make treated wastewater re-usable for industrial, agricultural, and domestic purposes. Membrane technology has emerged as a favorite choice for reclaiming water from different wastewater streams for re-use. This review looks at the trending membrane technologies in wastewater treatment, their advantages and disadvantages. It also discusses membrane fouling, membrane cleaning, and membrane modules. Finally, recommendations for future research pertaining to the application of membrane technology in wastewater treatment are made.
Liposomes Loaded with the Proteasome Inhibitor Z-Leucinyl-Leucinyl-Norleucinal Are Effective in Inducing Apoptosis in Colorectal Cancer Cell Lines
Authors: Cortese Katia , Marconi Silvia , Aiello Cinzia , Gagliani Maria Cristina , Pilato Serena , Zappacosta Romina , Fontana Antonella , Castagnola Patrizio
Published: May 2020

Colorectal cancer (CRC) is one of the main causes of cancer-related death in developed countries. Targeted therapies and conventional chemotherapeutics have been developed to help treat this type of aggressive cancer. Among these, the monoclonal antibodies cetuximab (Cxm) and panitumumab specifically target and inactivate the signaling of ERBB1 (EGF receptor), a key player in the development and progression of this cancer. Unfortunately, these antibodies are effective only on a small fraction of patients due to primary or secondary/acquired resistance. However, as ERBB1 cell surface expression is often maintained in resistant tumors, ERBB1 can be exploited as a target to deliver other drugs. Liposomes and immunoliposomes are under intensive investigation as pharmaceutical nanocarriers and can be functionalized with specific antibodies. In this study, we first investigated the anti-cancer activity of a cell permeable tripeptide, leucine-leucin-norleucinal (LLNle), an inhibitor of gamma-secretase and proteasome, in three different CRC cell lines that express ERBB1. We formulated LLNle-liposomes and Cxm-conjugated LLNle-loaded liposomes (LLNle-immunoliposomes) and evaluated their efficacy in inhibiting cell survival. Despite similar pro-apoptotic effects of free LLNle and LLNle-liposomes, immunoliposomes-LLNle were significantly less effective than their unconjugated counterparts. Indeed, immunoliposomes-LLNle were readily internalized and trafficked to lysosomes, where LLNle was likely trapped and/or inactivated. In conclusion, we demonstrated that LLNle was readily delivered to CRC cell lines by liposomes, but immunoliposomes-LLNle failed to show significant anti-cancer activity.
Direct Fabrication of Ultra-Sensitive Humidity Sensor Based on Hair-Like Laser-Induced Graphene Patterns
Authors: Lee Jun-Uk , Ma Yong-Won , Jeong Sung-Yeob , Shin Bo-Sung
Published: May 2020

Three-dimensional (3-D) porous graphitic structures have great potential for sensing applications due to their conductive carbon networks and large surface area. In this work, we present a method for facile fabrication of hair-like laser induced graphene (LIG) patterns using a laser scribing system equipped with a 355 nm pulsed laser. The polyimide (PI) film was positioned on a defocused plane and irradiated at a slow scanning speed using a misaligned laser beam. These patterns have the advantages of a large surface area and abundant oxidation groups. We have applied the hair-like LIG patterns to a humidity sensor. The humidity sensor showed good sensitivity characteristics and a large amount of electronic carriers can be stored.
Hydrogel Patterns in Microfluidic Devices by Do-It-Yourself UV-Photolithography Suitable for Very Large-Scale Integration
Authors: Beck Anthony , Obst Franziska , Busek Mathias , Grünzner Stefan , Mehner Philipp , Paschew Georgi , Appelhans Dietmar , Voit Brigitte , Richter Andreas
Published: May 2020

The interest in large-scale integrated (LSI) microfluidic systems that perform high-throughput biological and chemical laboratory investigations on a single chip is steadily growing. Such highly integrated Labs-on-a-Chip (LoC) provide fast analysis, high functionality, outstanding reproducibility at low cost per sample, and small demand of reagents. One LoC platform technology capable of LSI relies on specific intrinsically active polymers, the so-called stimuli-responsive hydrogels. Analogous to microelectronics, the active components of the chips can be realized by photolithographic micro-patterning of functional layers. The miniaturization potential and the integration degree of the microfluidic circuits depend on the capability of the photolithographic process to pattern hydrogel layers with high resolution, and they typically require expensive cleanroom equipment. Here, we propose, compare, and discuss a cost-efficient do-it-yourself (DIY) photolithographic set-up suitable to micro-pattern hydrogel-layers with a resolution as needed for very large-scale integrated (VLSI) microfluidics. The achievable structure dimensions are in the lower micrometer scale, down to a feature size of 20 µm with aspect ratios of 1:5 and maximum integration densities of 20,000 hydrogel patterns per cm². Furthermore, we demonstrate the effects of miniaturization on the efficiency of a hydrogel-based microreactor system by increasing the surface area to volume (SA:V) ratio of integrated bioactive hydrogels. We then determine and discuss a correlation between ultraviolet (UV) exposure time, cross-linking density of polymers, and the degree of immobilization of bioactive components.
A Rapid Method for Selecting Non-Saccharomyces Strains with a Low Ethanol Yield
Authors: Zhu Xiaolin , Navarro Yurena , Mas Albert , Torija María-Jesús , Beltran Gemma
Published: May 2020

The alcohol content in wine has increased due to external factors in recent decades. In recent reports, some non-Saccharomyces yeast species have been confirmed to reduce ethanol during the alcoholic fermentation process. Thus, an efficient screening of non-Saccharomyces yeasts with low ethanol yield is required due to the broad diversity of these yeasts. In this study, we proposed a rapid method for selecting strains with a low ethanol yield from forty-five non-Saccharomyces yeasts belonging to eighteen species. Single fermentations were carried out for this rapid selection. Then, sequential fermentations in synthetic and natural must were conducted with the selected strains to confirm their capacity to reduce ethanol compared with that of Saccharomyces cerevisiae. The results showed that ten non-Saccharomyces strains were able to reduce the ethanol content, namely, Hanseniaspora uvarum (2), Issatchenkia terricola (1), Metschnikowia pulcherrima (2), Lachancea thermotolerans (1), Saccharomycodes ludwigii (1), Torulaspora delbrueckii (2), and Zygosaccharomyces bailii (1). Compared with S. cerevisiae, the ethanol reduction of the selected strains ranged from 0.29 to 1.39% (v/v). Sequential inoculations of M. pulcherrima (Mp51 and Mp FA) and S. cerevisiae reduced the highest concentration of ethanol by 1.17 to 1.39% (v/v) in synthetic or natural must. Second, sequential fermentations with Z. bailii (Zb43) and T. delbrueckii (Td Pt) performed in natural must yielded ethanol reductions of 1.02 and 0.84% (v/v), respectively.
Virulence Characteristics of mecA-Positive Multidrug-Resistant Clinical Coagulase-Negative Staphylococci
Authors: Chon Jung-Whan , Lee Un Jung , Bensen Ryan , West Stephanie , Paredes Angel , Lim Jinhee , Khan Saeed , Hart Mark E. , Phillips K. Scott , Sung Kidon
Published: May 2020

Coagulase-negative staphylococci (CoNS) are an important group of opportunistic pathogenic microorganisms that cause infections in hospital settings and are generally resistant to many antimicrobial agents. We report on phenotypic and genotypic virulence characteristics of a select group of clinical, mecA-positive (encoding penicillin-binding protein 2a) CoNS isolates. All CoNS were resistant to two or more antimicrobials with S. epidermidis strain 214EP, showing resistance to fifteen of the sixteen antimicrobial agents tested. Aminoglycoside-resistance genes were the ones most commonly detected. The presence of megaplasmids containing both horizontal gene transfer and antimicrobial resistance genetic determinants indicates that CoNS may disseminate antibiotic resistance to other bacteria. Staphylococcus sciuri species produced six virulence enzymes, including a DNase, gelatinase, lipase, phosphatase, and protease that are suspected to degrade tissues into nutrients for bacterial growth and contribute to the pathogenicity of CoNS. The PCR assay for the detection of biofilm-associated genes found the eno (encoding laminin-binding protein) gene in all isolates. Measurement of their biofilm-forming ability and Spearman’s rank correlation coefficient analyses revealed that the results of crystal violet (CV) and extracellular polymeric substances (EPS) assays were significantly correlated (ρ = 0.9153, P = 3.612e-12). The presence of virulence factors, biofilm-formation capability, extracellular enzymes, multidrug resistance, and gene transfer markers in mecA-positive CoNS clinical strains used in this study makes them powerful opportunistic pathogens. The study also warrants a careful evaluation of nosocomial infections caused by CoNS and may be useful in studying the mechanism of virulence and factors associated with their pathogenicity in vivo and developing effective strategies for mitigation.
Characterization of Simple Sequence Repeats (SSRs) in Ciliated Protists Inferred by Comparative Genomics
Authors: Li Yuan , Chen Xiao , Wu Kun , Pan Jiao , Long Hongan , Yan Ying
Published: May 2020

Simple sequence repeats (SSRs) are prevalent in the genomes of all organisms. They are widely used as genetic markers, and are insertion/deletion mutation hotspots, which directly influence genome evolution. However, little is known about such important genomic components in ciliated protists, a large group of unicellular eukaryotes with extremely long evolutionary history and genome diversity. With recent publications of multiple ciliate genomes, we start to get a chance to explore perfect SSRs with motif size 1–100 bp and at least three motif repeats in nine species of two ciliate classes, Oligohymenophorea and Spirotrichea. We found that homopolymers are the most prevalent SSRs in these A/T-rich species, with AAA (lysine, charged amino acid; also seen as an SSR with one-adenine motif repeated three times) being the codons repeated at the highest frequencies in coding SSR regions, consistent with the widespread alveolin proteins rich in lysine repeats as found in Tetrahymena. Micronuclear SSRs are universally more abundant than the macronuclear ones of the same motif-size, except for the 8-bp-motif SSRs in extensively fragmented chromosomes. Both the abundance and A/T content of SSRs decrease as motif-size increases, while the abundance is positively correlated with the A/T content of the genome. Also, smaller genomes have lower proportions of coding SSRs out of all SSRs in Paramecium species. This genome-wide and cross-species analysis reveals the high diversity of SSRs and reflects the rapid evolution of these simple repetitive elements in ciliate genomes.