bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensor Control in Anti-Submarine Warfare—A Digital Twin and Random Finite Sets Based Approach
Authors: Wang Peng , Yang Mei , Peng Yong , Zhu Jiancheng , Ju Rusheng , Yin Quanjun
Published: August 2019

Since the submarine has become the major threat to maritime security, there is an urgent need to find a more efficient method of anti-submarine warfare (ASW). The digital twin theory is one of the most outstanding information technologies, and has been quite popular in recent years. The most influential change produced by digital twin is the ability to enable real-time dynamic interactions between the simulation world and the real world. Digital twin can be regarded as a paradigm by means of which selected online measurements are dynamically assimilated into the simulation world, with the running simulation model guiding the real world adaptively in reverse. By combining digital twin theory and random finite sets (RFSs) closely, a new framework of sensor control in ASW is proposed. Two key algorithms are proposed for supporting the digital twin-based framework. First, the RFS-based data-assimilation algorithm is proposed for online assimilating the sequence of real-time measurements with detection uncertainty, data association uncertainty, noise, and clutters. Second, the computation of the reward function by using the results of the proposed data-assimilation algorithm is introduced to find the optimal control action. The results of three groups of experiments successfully verify the feasibility and effectiveness of the proposed approach.
The Evolution of the Key Sectors in the Philippine Economy Using an AHP-Based Sector Prioritization Index
Authors: Go Daryn Joy , Promentilla Michael Angelo , Aviso Kathleen , Yu Krista Danielle
Published: August 2019

Economic sectors play a vital role in ensuring that government’s goals are achieved. This study analyzes the evolution of the structure and key sectors of an economy through the use of a sector prioritization index. This methodology integrates input-output analysis and analytic hierarchy process to determine the structural changes experienced by the economy, while accounting for the changes in the government’s priorities and concerns over time. Using the case of the Philippines from 1969 to 2012, this study shows a time-series analysis of the transformation that the economy underwent alongside with the government’s prioritization mechanism. We found that the manufacturing sector had consistently received high-priority rankings, while the agriculture sector had recently moved from a high- to mid-priority ranking, indicating the country’s shift towards a more industry-driven economy. These findings were supported by the private services and trade sectors’ high-priority rankings towards the latter half of the time period. Overall, our methodology was able to identify key sectors that reflect the country’s economic and political situation across different eras.
An Empirical Study on the Determinants of an Investor’s Decision in Unit Trust Investment
Authors: Annamalah Sanmugam , Raman Murali , Marthandan Govindan , Logeswaran Aravindan Kalisri
Published: August 2019

Unit trust is a convenient way of investing and a sensible way to build one’s wealth in the medium term and subsequently in the long-term. Investment specialists will manage the investments and spread the risks through careful diversification. The basic nature of the unit trust is that it carries a low-level of risks and accordingly determines a lower level of returns compared to other financial instruments. There is a lack of research that empirically investigates the factors that influence an investor’s decision in unit trust investment, particularly in a Malaysian setting. The purpose of this study is to analyse the factors that influence an investor’s investment decision in purchasing a unit trust. This paper aims to narrow this research gap, whereby financial status, risk taking behaviour, investment revenue and related information are hypothesized to exert statistically significant influences on the investor’s decision in unit trust investment. The empirical study uses a quantitative research approach whereby survey data have been sampled from 202 participants using a convenient sampling technique. This research is cross-sectional and uses primary data for analysis. Data analysis has been carried out using multiple regression analysis. The empirical research finds that financial status, risk taking behaviour, and sources of information significantly influence the investors’ investment behaviours in unit trusts. However, there was not enough evidence to support the claims that investment return and revenue have a statistical relationship to the investors investment behaviours regarding unit trusts. The findings from this research will have huge implications for investors and for financial institutions. This paper helps fund managers and brokers to understand the behaviours of an individual investor in response to a unit trust. On the other hand, this helps them to better target their customers, and persuade customers to make their investments in a unit trust effectively and efficiently, thereby helping them to manage their financial wealth with less risk but better future prospects.
Potential of District Cooling Systems: A Case Study on Recovering Cold Energy from Liquefied Natural Gas Vaporization
Authors: Mugnini Alice , Coccia Gianluca , Polonara Fabio , Arteconi Alessia
Published: August 2019

District cooling systems (DCSs) are networks able to distribute thermal energy, usually as chilled water, from a central source to industrial, commercial, and residential consumers, to be used for space cooling/dehumidification. As cooling demand will increase significantly in the next decades, DCSs can be seen as efficient solutions to improve sustainability. Although DCSs are considered so relevant for new city developments, there are still many technical, economic, and social issues to be overcome to let such systems to spread out. Thus, this paper aims to highlight the advantages and issues linked to the adoption of DCSs for building cooling when cold is recovered from a specific application. A case study based on liquified natural gas (LNG) cold energy recovery from the transport sector is presented. Starting from the estimation of the free cooling availability, a DCS design method is proposed and the potential energy saving is investigated. Results show that a DCS using the cold waste derived from LNG can provide a relevant amount of electricity saving (about 60%) for space cooling compared to traditional solutions, in which standard air conditioning systems are installed in every building.
Fault-Ride Trough Validation of IEC 61400-27-1 Type 3 and Type 4 Models of Different Wind Turbine Manufacturers
Authors: Honrubia-Escribano Andrés , Jiménez-Buendía Francisco , Sosa-Avendaño Jorge Luis , Gartmann Pascal , Frahm Sebastian , Fortmann Jens , Sørensen Poul Ejnar , Gómez-Lázaro Emilio
Published: August 2019

The participation of wind power in the energy mix of current power systems is progressively increasing, with variable-speed wind turbines being the leading technology in recent years. In this line, dynamic models of wind turbines able to emulate their response against grid disturbances, such as voltage dips, are required. To address this issue, the International Electronic Commission (IEC) 61400-27-1, published in 2015, defined four generic models of wind turbines for transient stability analysis. To achieve a widespread use of these generic wind turbine models, validations with field data are required. This paper performs the validation of three generic IEC 61400-27-1 variable-speed wind turbine model topologies (type 3A, type 3B and type 4A). The validation is implemented by comparing simulation results with voltage dip measurements performed on six different commercial wind turbines based on field campaigns conducted by three wind turbine manufacturers. Both IEC validation approaches, the play-back and the full system simulation, were implemented. The results show that the generic full-scale converter topology is accurately adjusted to the different real wind turbines and, hence, manufacturers are encouraged to the develop generic IEC models.
Heat Transfer Enhancement of TiO2/Water Nanofluids Flowing Inside a Square Minichannel with a Microfin Structure: A Numerical Investigation
Authors: Kristiawan Budi , Wijayanta Agung Tri , Enoki Koji , Miyazaki Takahiko , Aziz Muhammad
Published: August 2019

A combination of two passive heat transfer enhancement techniques using a microfin structure and nanofluids was investigated numerically. TiO2/water nanofluids flowing inside a square minichannel with a microfin structure (SMM) were observed as a practical application. Increased heat transfer performance was investigated by observing the Nusselt number, friction factor, and performance evaluation criterion (PEC). Velocity and temperature profiles were also demonstrated at a laminar developing flow regime. The SMM used in this work had six microfins (N = 6) and TiO2/water nanofluids with various nanoparticle concentrations of 0.005, 0.01, and 0.1 vol.%. By combining nanofluids as working fluids and SMM as a passive heat transfer enhancement, the maximum PEC value of 1.2 was achieved at Re = 380 with a volume fraction of 0.01 vol.%. It is obvious that compared to water flowing inside the square minichannel microfin, the heat transfer can be increased by using only a nanofluid with a volume fraction of 0.01%. The combination of a microfin and nanofluids as working fluids is strongly recommended due to its excellent performance in terms of heat transfer and economic considerations.
Effect of Various Cooking Methods on Technological and Sensory Quality of Atlantic Salmon (Salmo salar)
Authors: Głuchowski Artur , Czarniecka-Skubina Ewa , Wasiak-Zys Grażyna , Nowak Dorota
Published: August 2019

The aim of the study was to evaluate the effect of heat treatment salmon quality using the sous-vide method (57 °C, 20 min and 63 °C, 80 min) in comparison with traditional methods (steam cooking, roasting). The yield of process and sensory quality (sensory profile, consumer liking) and the color and texture of salmon was measured. Salmon processed with the sous-vide method was characterized by a statistically significantly (p ≤ 0.05) higher yield and water content than the samples prepared by steaming and roasting. Statistically higher (p ≤ 0.05) consumer preference for salmon prepared using higher parameters of the sous-vide process (63 °C, 80 min) compared with low parameters (57 °C, 20 min) was stated. Parameters of the sous-vide processing (57 °C, 20 min) have a negative effect on salmon quality. It was observed that as the temperature and time of the process increased, the intensity of the flavor and odor attributes of cooked fish also increased, while the intensity of raw fish, juiciness, tenderness, and softness decreased. The color of salmon also changed. Based on the results, we recommend the following parameters of process in preparing salmon using the sous-vide method: 63 °C for 80 min.
Trans-Species Polymorphism in Mitochondrial Genome of Camarodont Sea Urchins
Authors: Balakirev Evgeniy S.
Published: August 2019

Mitochondrial (mt) genomes of the sea urchins Strongylocentrotus intermedius and Mesocentrotus nudus demonstrate the identical patterns of intraspecific length variability of the ND6 gene, consisting of 489 bp (S variant) and 498 bp (L variant), respectively. For both species, the ND6 length difference is due to the 488A>G substitution, which changes the stop codon TAG in S variant for a tryptophan codon TGG in L variant and elongates the corresponding ND6 protein by three additional amino acids, Trp-Leu-Trp. The phylogenetic analysis based on mt genomes of sea urchins and related echinoderm groups from GenBank has shown the S and L ND6 variants as shared among the camarodont sea urchins; the rest of the echinoderms demonstrate the S variant only. The data suggest that the ND6 488A>G substitution can be the first example of the trans-species polymorphism in sea urchins, persisting at least since the time of the Odontophora diversification at the Eocene/Oligocene boundary (approximately 34 million years ago), which was characterized by an abrupt climate change and significant global ocean cooling. Alternative hypotheses, including the convergent RNA editing and/or codon reassignment, are not supported by direct comparisons of the ND6 gene sequences with the corresponding transcripts using the basic local alignment search tool (BLAST) of full sea urchin transcriptomes.
The Meaning of the Common World in Perioperative Nursing Care; A Hermeneutic Study
Authors: Lindberg Susan , Rudolfsson Gudrun
Published: August 2019

The aim of this study is to bring forth the meaning of the common world as it appears in perioperative nursing care. We employed the epistemological standpoints of preunderstanding, the hermeneutic spiral and fusion of horizons grounded in Gadamer’s hermeneutic philosophy as well as Eriksson’s Theory of Caritative Caring based on the ontology of caring science, where caritas is the basic motive and ethos of caring. Four hermeneutic spiral activities were performed, consisting of a mimetic presentation bearing the ontological depth of the common world, its distinctive features, the universal and lasting and finally, the truth inherent in the common world. The inherent truth of the common world is the prevalence of harmony, wholeness and the idea of love, mercy and reverence for human dignity. The common world brings ethics to existence, achieved by the word of honour, which in its true being makes visible the universal and ontological horizons of a common reality. The common world is the creation of a hermeneutic movement inside each suffering human being, where the boundless life-giving time represents the inhabited movement of time, like coming home.
Drought and Desertification in Iran
Authors: Emadodin Iraj , Reinsch Thorsten , Taube Friedhelm
Published: August 2019

Iran has different climatic and geographical zones (mountainous and desert areas), mostly arid and semi-arid, which are suffering from land degradation. Desertification as a land degradation process in Iran is created by natural and anthropogenic driving forces. Meteorological drought is a major natural driving force of desertification and occurs due to the extended periods of low precipitation. Scarcity of water, as well as the excessive use of water resources, mainly for agriculture, creates negative water balances and changes in plant cover, and accelerates desertification. Despite various political measures having been taken in the past, desertification is still a serious environmental problem in many regions in Iran. In this study, drought and aridity indices derived from long-term temperature and precipitation data were used in order to show long-term drought occurrence in different climatic zones in Iran. The results indicated the occurrence of severe and extremely severe meteorological droughts in recent decades in the areas studied. Moreover, the De Martonne Aridity Index (IDM) and precipitation variability index (PVI) showed an ongoing negative trend on the basis of long-term data and the conducted regression analysis. Rapid population growth, soil salinization, and poor water resource management are also considered as the main anthropogenic drivers. The percentage of the rural population in Iran is decreasing and the urban area is growing fast. Since the 1970s, the usage of groundwater in Iran has increased around fourfold and the average annual decrease in the groundwater table has been around 0.51 m. The results of the study provide a better ex-post and ex-ante understanding of the occurrence of droughts as key driving forces of the desertification in Iran. Additionally, they can enable policymakers to prepare proper regional-based strategic planning in the future. Desertification cannot be stopped or managed completely, but could be mitigated by the adoption of some proposed sustainable land management strategies.
F-Spondin Is the Signal by Which 2-Methoxyestradiol Induces Apoptosis in the Endometrial Cancer Cell Line Ishikawa
Authors: Rincón-Rodriguez Ramiro , Mena Dennise , Mena Javier , Díaz-Saldivar Patricia , Guajardo-Correa Emanuel , Godoy-Guzman Carlos , Cardenas Hugo , Orihuela Pedro A.
Published: August 2019

The metabolite 2-methoxyestradiol (2ME) is an endogenous estrogen metabolite with potential therapeutic properties in reproductive cancers. However, the molecular mechanisms by which 2ME exerts its anticancer activity are not well elucidated. The purpose of this study was to determine the molecular signals associated with the apoptotic effects of 2ME in a human endometrial cancer cell line. Ishikawa cells were treated with non-apoptotic (0.1 µM) or apoptotic concentrations (5 µM) of 2ME, and 12 hours later mRNA levels for Scd2, Snx6, and Spon1 were determined by real-time PCR. We then investigated by immunofluorescence and Western blot the expression and distribution of F-spondin, encoded by Spon1, in Ishikawa cells treated with 2ME 5 µM at 6, 12, or 24 h after treatment. The role of estrogen receptors (ER) in the effect of 2ME on the Spon1 level was also investigated. Finally, we examined whether 2ME 5 µM induces cell death in Ishikawa cells pre-incubated with a neutralizing F-spondin antibody. Non-apoptotic or apoptotic concentrations of 2ME decreased Scd2 and increased Snx6. However, Spon1 was only increased with the 2ME apoptotic concentration. F-spondin protein was also increased at 12 and 24 h after 2ME treatment, while 2ME-induced Spon1 increase was independent of ER. Neutralization of F-spondin blocked the effect of 2ME on the cell viability. These results show that F-spondin signaling is one of the components in the apoptotic effects of 2ME on Ishikawa cells and provide experimental evidence underlying the mechanism of action of this estrogen metabolite on cancer cells.
Setting Fire to ESA and EMA Resistance: New Targeted Treatment Options in Lower Risk Myelodysplastic Syndromes
Authors: Kubasch Anne Sophie , Platzbecker Uwe
Published: August 2019

During the last decade, substantial advances have been made in the understanding of the complex molecular, immunological and cellular disturbances involved in the initiation as well as evolution of myelodysplastic syndromes (MDS). In 85% of the mainly frail and older patient population, anemia is present at the time of diagnosis and is thus a major therapeutic challenge. High rates of primary resistance to erythropoiesis-stimulating agents (ESAs), the currently only approved standard therapy to treat anemia in lower-risk MDS, demand the development of novel and efficient drugs with a good safety profile. Luspatercept, a ligand trap of activin receptor II, is able to promote late stage erythropoiesis even in patients failing prior ESA treatment. The presence of ring sideroblastic phenotype defines a subgroup of patients with higher response rates. Additionally, recent developments in clinical research using HIF-1 or telomerase modulation by roxadustat or imetelstat are promising. Other areas of translational research involve targeting the inflammasome by anti-inflammatory drugs in order to improve anemia. These efforts will hopefully pave the way for new targeted treatment options for anemic low-risk MDS patients.
Comparison of Lithium-Ion Battery Models for Simulating Storage Systems in Distributed Power Generation
Authors: Hinz Hartmut
Published: August 2019

Lithium-ion batteries are well known in numerous commercial applications. Using accurate and efficient models, system designers can predict the behavior of batteries and optimize the associated performance management. Model-based development comprises the investigation of electrical, electro-chemical, thermal, and aging characteristics. This paper focuses on the analysis of models describing the electrical behavior. In particular, it investigates how cell voltage and state of charge can be determined with sufficient accuracy for a given load profile. For this purpose, the Thevenin-based, the Rint, and the Shepherd’s models, as well as a generic library model of an electronic circuit simulation software package, are compared. The procedure for determining model parameters is discussed in detail. All models are evaluated for the application in the analysis of distributed power generation. The validation is carried out by comparing simulation and measurement results with the help of a case study.
Friction vs. Area Scaling of Superlubric NaCl-Particles on Graphite
Authors: Hartmuth Felix , Dietzel Dirk , de Wijn Astrid S. , Schirmeisen André
Published: August 2019

Structural lubricity is an intriguing tribological concept, where extremely low friction is anticipated, if two surfaces in relative motion do not share the same lattice structure and consequently instabilities originating from interlocking surface potentials are strongly reduced. Currently, the challenges related to the phenomenon of structural lubricity are considered to be twofold. On one hand, experimental systems suitable for showing structural lubricity must be identified, while at the same time, it is also crucial to understand the intricate details of interface interaction. Here, we introduce a new material combination, namely NaCl-particles on highly oriented pyrolithic graphite (HOPG), where the nanoparticles coalesce under the influence of ambient humidity. Our experiments reveal that the interfacial friction can be described by the concept of structural lubricity despite the seemingly unavoidable contamination of the interface. By systematically analyzing the friction versus area scaling, this unlikely candidate for structural lubricity then shows two separate friction branches, with distinct differences of the friction versus area scaling. The exact tribological behavior of the nanoparticles can ultimately be understood by a model that considers the influence of nanoparticle preparation on the interface conditions. By taking into account an inevitable water layer at the interface between particle and substrate that can exist in different crystalline configurations all friction phenomena observed in the experiments can be understood.
Isothermal Crystallization Kinetics of Poly(4-hydroxybutyrate) Biopolymer
Authors: Keridou Ina , del Valle Luis J. , Funk Lutz , Turon Pau , Yousef Ibraheem , Franco Lourdes , Puiggalí Jordi
Published: August 2019

Thermal properties and crystallization kinetics of poly(4-hydroxybutyrate) (P4HB) have been studied. The polymer shows the typical complex melting behavior associated to different lamellar populations. Annealing processes had great repercussions on properties and the morphology of constitutive lamellae as verified by X-ray scattering data. Kinetics of isothermal crystallization was evaluated by both polarizing optical microscopy (POM) and calorimetric (DSC) measurements, which indicated a single crystallization regime. P4HB rendered banded spherulites with a negative birefringence when crystallized from the melt. Infrared microspectroscopy was applied to determine differences on the molecular orientation inside a specific ring according to the spherulite sectorization or between different rings along a determined spherulitic radius. Primary nucleation was increased during crystallization and when temperature decreased. Similar crystallization parameters were deduced from DSC and POM analyses (e.g., secondary nucleation parameters of 1.69 × 105 K2 and 1.58 × 105 K2, respectively). The effect of a sporadic nucleation was therefore minimized in the experimental crystallization temperature range and a good proportionality between overall crystallization rate (k) and crystal growth rate (G) was inferred. Similar bell-shaped curves were postulated to express the temperature dependence of both k and G rates, corresponding to the maximum of these curves close to a crystallization temperature of 14–15 °C.
Bending Strain and Bending Fatigue Lifetime of Flexible Metal Electrodes on Polymer Substrates
Authors: Kim Tae-Wook , Lee Jong-Sung , Kim Young-Cheon , Joo Young-Chang , Kim Byoung-Joon
Published: August 2019

As the technology of flexible electronics has remarkably advanced, the long-term reliability of flexible devices has attracted much attention, as it is an important factor for such devices in reaching real commercial viability. To guarantee the bending fatigue lifetime, the exact evaluation of bending strain and the change in electrical resistance is required. In this study, we investigated the bending strains of Cu thin films on flexible polyimide substrates with different thicknesses using monolayer and bilayer bending models and monitored the electrical resistance of the metal electrode during a bending fatigue test. For a thin metal electrode, the bending strain and fatigue lifetime were similar regardless of substrate thickness, but for a thick metal film, the fatigue lifetime was changed by different bending strains in the metal electrode according to substrate thickness. To obtain the exact bending strain distribution, we conducted a finite-element simulation and compared the bending strains of thin and thick metal structures. For thick metal electrodes, the real bending strain obtained from a bilayer model or simulation showed values much different from those from a simple monolayer model. This study can provide useful guidelines for developing highly reliable flexible electronics.
The Interface and Mechanical Properties of a CVD Single Crystal Diamond Produced by Multilayered Nitrogen Doping Epitaxial Growth
Authors: Zhao Yun , Li Chengming , Liu Jinlong , An Kang , Yan Xiongbo , Hei Lifu , Chen Liangxian , Wei Junjun , Lu Fanxiu
Published: August 2019

In the present investigation, a nitrogen-doped multilayer homoepitaxial single crystal diamond is synthesized on a high-pressure high temperature (HPHT) Ib-type diamond substrate using the microwave plasma chemical vapor deposition (MPCVD) method. When 0.15 sccm of nitrogen was added in the gas phase, the growth rate of the doped layer was about 1.7 times that of the buffer layer, and large conical and pyramidal features are formed on the surface of the sample. Raman mapping and photoluminescence imaging of the polished cross sectional slice shows a broadband emission, with a characteristic zero phonon line (ZPL) at 575 nm in the doped layers, and large compressive stress was formed in the nitrogen-doped layers. X-ray topography shows that the defects at the interface can induce dislocation. The pyramid feature is formed at the defect, and more nitrogen-related defects are formed in the pyramid region. Thin nitrogen-doped multilayers were successfully prepared, and the thickness of the nitrogen-doped and buffer layers was about 650 nm each. The indentation measurements reveal that the thin nitrogen-doped multilayers are ultra-tough (at least ~22 MPa m1/2), compared to the Ib-type HPHT seed substrate (~8 MPa m1/2) and the unintentionally doped chemical vapor deposition (CVD) single crystal diamond (~14 MPa m1/2).
Improvement of Surface Roughness and Hydrophobicity in PETG Parts Manufactured via Fused Deposition Modeling (FDM): An Application in 3D Printed Self–Cleaning Parts
Authors: Barrios Juan M. , Romero Pablo E.
Published: August 2019

The fused deposition modeling (FDM) technique is used today by companies engaged in the fabrication of traffic signs for the manufacture of light-emitting diode LED spotlights. In this sector, the surface properties of the elements used (surface finish, hydrophobic features) are decisive because surfaces that retain little dirt and favor self–cleaning behavior are needed. A design of experiments (L27) with five factors and three levels has been carried out. The factors studied were: Layer height (LH), print temperature (T), print speed (PS), print acceleration (PA), and flow rate (F). Polyethylene terephthalate glycol (PETG) specimens of 25.0 × 25.0 × 2.4 mm have been printed and, in each of them, the surface roughness (Ra,0, Ra,90), sliding angle (SA0, SA90), and contact angle (CA0, CA90) in both perpendicular directions have been measured. Taguchi and ANOVA analysis shows that the most influential variables in this case are printing acceleration for Ra, 0 (p–value = 0.052) and for SA0 (p–value = 0.051) and flow rate for Ra, 90 (p–value = 0.001) and for SA90 (p–value = 0.012). Although the ANOVA results for the contact angle are not significant, specimen 8 (PA = 1500 mm/s2 and flow rate F = 110%) and specimen 10 (PA =1500 mm/s2 and F = 100%) have reached contact angle values above or near the limit value for hydrophobia, respectively.
Co-Blend Application Mode of Bulk Fill Composite Resin
Authors: Al-Nabulsi Mohammad , Daud Alaa , Yiu Cynthia , Omar Hanan , Sauro Salvatore , Fawzy Amr , Daood Umer
Published: August 2019

Objective: To evaluate the effect of a new application method of bulk-fill flowable composite resin material on bond-strength, nanoleakage, and mechanical properties of dentine bonding agents. Materials and methods: Sound extracted human molars were randomly divided into: manufacturer’s instructions (MI), manual blend 2 mm (MB2), and manual blend 4 mm (MB4). Occlusal enamel was removed and flattened, dentin surfaces were bonded by Prime & Bond universal (Dentsply and Optibond FL, Kerr). For the MI group, adhesives were applied following the manufacturer’s instructions then light-cured. For MB groups, SDR flow+ bulk-fill flowable composite resin was applied in 2- or 4-mm increment then manually rubbed by a micro brush for 15 s with uncured dentine bonding agents and the mixture was light-cured. Composite buildup was fabricated incrementally using Ceram.X One, Dentsply nanohybrid composite resin restorative material. After 24-h water storage, the teeth were sectioned to obtain beams of about 0.8 mm2 for 24-h and thermocycled micro-tensile bond strength at 0.5 mm/min crosshead speed. Degree of conversion was evaluated with micro-Raman spectroscopy. Contraction gaps at 24 h after polymerization were evaluated and atomic force microscopy (AFM) nano-indentation processes were undertaken for measuring the hardness across the interface. Depth of resin penetration was studied using a scanning electron microscope (SEM). Bond strength data was expressed using two-way ANOVA followed by Tukey’s test. Nanoindentation hardness was separately analyzed using one-way ANOVA. Results: Factors “storage F = 6.3” and “application F = 30.11” significantly affected the bond strength to dentine. For Optibond FL, no significant difference in nanoleakage was found in MI/MB4 groups between baseline and aged specimens; significant difference in nanoleakage score was observed in MB2 groups. Confocal microscopy analysis showed MB2 Optibond FL and Prime & Bond universal specimens diffusing within the dentine. Contraction gap was significantly reduced in MB2 specimens in both adhesive systems. Degree of conversion (DC) of the MB2 specimens were numerically more compared to MS1 in both adhesive systems. Conclusion: Present study suggests that the new co-blend technique might have a positive effect on bond strengths of etch-and-rinse adhesives to dentine.
Effect of Gradient Heat Treatment on Microstructure and Properties of Cu–Al–Mn Shape Memory Alloy
Authors: Zhou Luohui , Lan Jingling , Liu Jili , Li Xu , Shi Bowen , Zheng Shuyang
Published: August 2019

The columnar-grained Cu–Al–Mn shape memory alloys (SMAs), which have good shape memory properties and are prepared by a unidirectional solidification technique, were subjected to a gradient heat treatment under temperatures ranging from 100 to 450 °C. After this treatment, the microstructure, hardness, transformation temperature and shape memory properties of these samples could exhibit gradient changing trends, all of which were investigated by optical microscope, scanning electron microscopy (SEM), a Vickers microhardness tester, and a compression machine. The microstructure observation result shows that the acicular bainite-precipitated phase produces from scratch and then grows continuously with the increasing of the heat treatment temperature, finally presenting a graded distribution from one end section to another of the sample. The hardness tests give the samples results also increasing with temperature. Specifically, the change relationship between hardness and the treatment temperature mathematically satisfies dynamic function. In addition, it can be concluded from mechanical tests the compressive elastic–superelastic strain and strength of the samples show gradient variation features. Overall, our experimental investigation indicates that a gradient heat treatment is an effective way to conduct microstructure control or design for the Cu–Al–Mn SMAs, and their graded properties are mainly caused by the different fractions of the bainite phase producing in different local areas after the gradient heat treatment.
The Strengthening and Toughening of Biodegradable Poly (Lactic Acid) Using the SiO2-PBA Core–Shell Nanoparticle
Authors: He Hailing , Pang Yuezhao , Duan Zhiwei , Luo Na , Wang Zhenqing
Published: August 2019

The balance of strengthening and toughening of poly (lactic acid) (PLA) has been an intractable challenge of PLA nanocomposite development for many years. In this paper, core–shell nanoparticles consisting of a silica rigid core and poly (butyl acrylate) (PBA) flexible shell were incorporated to achieve the simultaneous enhancement of the strength and toughness of PLA. The effect of core–shell nanoparticles on the tensile, flexural and Charpy impact properties of PLA nanocomposite were experimentally investigated. Scanning electron microscopy (SEM) and small-angle X-ray scattering (SAXS) measurements were performed to investigate the toughening mechanisms of nanocomposites. The experimental results showed that the addition of core–shell nanoparticles can improve the stiffness and strength of PLA. Meanwhile, its elongation at break, tensile toughness and impact resistance were enhanced simultaneously. These observations can be attributed to the cavitation of the flexible shell in core–shell nanoparticles and the resultant shear yielding of the matrix. In addition, a three-dimensional finite element model was also proposed to illustrate the damage processes of core–shell nanoparticle-reinforced polymer composites. It was found that, compared with the experimental performance, the proposed micromechanical model is favorable to illustrate the mechanical behavior of nanocomposites.
Experimental Study on Machining Engineering Ceramics by Electrochemical Discharge Compound Grinding
Authors: Xu Kun , Zhang Zhaoyang , Yang Jingbo , Zhu Hao , Fang Xiaolong
Published: August 2019

Since engineering ceramics have many characteristics, including hardness, brittleness, and high melting point, traditional machining methods can no longer play a useful role in precision machining. Based on this situation, a platform of electrochemical discharge compound mechanical grinding was constructed and is presented in this paper, and machining experiments of micro-grooves were carried out in alumina ceramics. Grooves were observed by scanning electron microscope (SEM), and the morphology and the groove width of micro-grooves under different machining parameters were compared and analyzed. Furthermore, in order to study the improvement effect of mechanical grinding on machining quality, the surface roughness of micro-grooves was measured by a confocal material microscope. The results show that as the pulse power supply voltage increases or the frequency decreases, the width of the micro-grooves increases, and the morphology of the micro-grooves first improves and then deteriorates. With the increase of tool electrode rotation speed, the width of micro-grooves first increases and then remains unchanged, and the morphology and the surface roughness of micro-grooves first improves and then remains stable. Finally, the optimal parameters (power voltage of 20 V, pulse frequency of 400 Hz, electrode rotation speed of 600 rpm) were chosen to machine micro-grooves with good quality.
Enhanced Adsorptive Properties and Pseudocapacitance of Flexible Polyaniline-Activated Carbon Cloth Composites Synthesized Electrochemically in a Filter-Press Cell
Authors: Quijada César , Leite-Rosa Larissa , Berenguer Raúl , Bou-Belda Eva
Published: August 2019

Electrochemical polymerization is known to be a suitable route to obtain conducting polymer-carbon composites uniformly covering the carbon support. In this work, we report the application of a filter-press electrochemical cell to polymerize polyaniline (PAni) on the surface of large-sized activated carbon cloth (ACC) by simple galvanostatic electropolymerization of an aniline-containing H2SO4 electrolyte. Flexible composites with different PAni loadings were synthesized by controlling the treatment time and characterized by means of Scanning Electron microscopy (SEM), X-Ray Photoelectron Spectroscopy (XPS), physical adsorption of gases, thermogravimetric analysis (TGA), cyclic voltammetry and direct current (DC) conductivity measurements. PAni grows first as a thin film mostly deposited inside ACC micro- and mesoporosity. At prolonged electropolymerization time, the amount of deposited PAni rises sharply to form a brittle and porous, thick coating of nanofibrous or nanowire-shaped structures. Composites with low-loading PAni thin films show enhanced specific capacitance, lower sheet resistance and faster adsorption kinetics of Acid Red 27. Instead, thick nanofibrous coatings have a deleterious effect, which is attributed to a dramatic decrease in the specific surface area caused by strong pore blockage and to the occurrence of contact electrical resistance. Our results demonstrate that mass-production restrictions often claimed for electropolymerization can be easily overcome.
Approximating Fixed Points of Bregman Generalized α-Nonexpansive Mappings
Authors: Muangchoo Kanikar , Kumam Poom , Cho Yeol Je , Dhompongsa Sompong , Ekvittayaniphon Sakulbuth
Published: August 2019

In this paper, we introduce a new class of Bregman generalized α -nonexpansive mappings in terms of the Bregman distance. We establish several weak and strong convergence theorems of the Ishikawa and Noor iterative schemes for Bregman generalized α -nonexpansive mappings in Banach spaces. A numerical example is given to illustrate the main results of fixed point approximation using Halpern’s algorithm.
Comparison of Physicochemical Characteristics and Fibril Formation Ability of Collagens Extracted from the Skin of Farmed River Puffer (Takifugu obscurus) and Tiger Puffer (Takifugu rubripes)
Authors: Wang Shan-Shan , Yu Ying , Sun Yong , Liu Nan , Zhou De-Qing
Published: August 2019

Acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from the skin of river puffer (ASC-RP and PSC-RP) and tiger puffer (ASC-TP and PSC-TP) were extracted and physicochemically examined. Denaturation temperature (Td) for all the collagens was found to be 25.5–29.5 °C, which was lower than that of calf skin collagen (35.9 °C). Electrophoretic patterns indicated all four samples were type I collagen with molecular form of (α1)2α2. FTIR spectra confirmed the extracted collagens had a triple-helical structure, and that the degree of hydrogen bonding in ASC was higher than PSC. All the extracted collagens could aggregate into fibrils with D-periodicity. The fibril formation rate of ASC-RP and PSC-RP was slightly higher than ASC-TP and PSC-TP. Turbidity analysis revealed an increase in fibril formation rate when adding a low concentration of NaCl (less than 300 mM). The fibril formation ability was suppressed with further increasing of NaCl concentration, as illustrated by a reduction in the turbidity and formation degree. SEM analysis confirmed the well-formed interwoven structure of collagen fibrils after 24 h of incubation. Summarizing the experimental results suggested that the extracted collagens from the skin of river puffer and tiger puffer could be considered a viable substitute to mammalian-derived collagens for further use in biomaterial applications.
Acute Exercise Intensity and Memory Function: Evaluation of the Transient Hypofrontality Hypothesis
Authors: Loprinzi Paul D. , Day Sierra , Deming Raymond
Published: August 2019

Background and Objective: The transient hypofrontality hypothesis predicts that memory function will be impaired during high-intensity exercise, as a result of a need for metabolic and cognitive resources to be allocated toward sustaining movement, as opposed to performing a cognitive task. The purpose of these experiments was to evaluate this transient hypofrontality hypothesis. Materials and Methods: Experiment 1 involved participants (n = 24; Mage = 21.9 years) completing four counterbalanced visits. Two visits evaluated working memory function, either at rest or during a high-intensity bout of acute exercise. The other two visits evaluated episodic memory function, either at rest or during a high-intensity bout of acute exercise. Experiment 2 (n = 24; Mage = 20.9 years) extended Experiment 1 by evaluating memory function (working memory) across 4 counterbalanced conditions, including at rest and during light (30% of heart rate reserve; HRR), moderate (50% HRR) and high-intensity (80% HRR) acute exercise. Results: Experiment 1 demonstrated that, when compared to rest, both working memory and episodic memory were impaired during high-intensity acute exercise. Experiment 2 replicated this effect, but then also showed that, unlike high-intensity acute exercise, memory function was not impaired during low- and moderate-intensity acute exercise. Conclusions: Our experiments provide support for the transient hypofrontality hypothesis. Both working memory and episodic memory are impaired during high-intensity acute exercise. Working memory does not appear to be impaired during lower exercise intensities.
High-Intensity Acute Exercise and Directed Forgetting on Memory Function
Authors: Pace Mary , Loprinzi Paul
Published: August 2019

Background and Objectives: Despite accumulating research demonstrating that acute exercise may enhance memory function, very little research has evaluated whether acute exercise can effectuate intentional directed forgetting (DF), an adaptative strategy to facilitate subsequent memory performance. Materials and Methods: A three-arm parallel-group randomized controlled intervention was employed. Participants were randomized into one of three groups, including: (1) exercise plus DF (Ex + DF), (2) DF (directed forgetting) only (DF) and (3) R (remember) only (R). The acute bout of exercise included 15 min of high-intensity treadmill exercise. The memory assessment involved the presentation of two-word lists. After encoding the first word list, participants were either instructed to forget all of those words (DF) or to remember them. Following this, participants encoded the second word list. Results: We observed a statistically significant main effect for list F(1, 57) = 12.27, p < 0.001, η2p = 0.18, but no main effect for group F(2, 57) = 1.32, p = 0.27, η2p = 0.04, or list by group interaction, F(2, 57) = 2.89, p = 0.06, η2p = 0.09. Conclusions: This study demonstrates a directed forgetting effect in that cueing an individual to forget a previously encoded list of items facilitates memory performance on a subsequent list of items. However, we failed to demonstrate any beneficial effect of acute exercise in facilitating directed forgetting. These findings are discussed in the context of directed forgetting theories, particularly the attention inhibition mechanism, as well as the timing of the acute bout of exercise.
Study of the Surface Integrity and High Cycle Fatigue Performance of AISI 4340 Steel after Composite Surface Modification
Authors: Fu Hai , Liang Yilong
Published: August 2019

In the field of materials science, the fabrication of a material with severe surface plastic deformation and a good surface state is an issue encountered in the development of counterbalanced gradient materials. For this paper, AISI 4340 steel was first processed with abrasive water jet peening (AWJP) and then with ultrasonic surface rolling (USRE) to obtain a good surface state while maintaining large plastic deformation. The AISI 4340 steel composite surface was therefore modified, and the surface integrity and cycle fatigue performance were analyzed. The results show that the plastic deformation layer of the modified composite surface of the 4340 steel was 310 µm from the surface of the sample, the grain size 40 µm from the surface layer was refined to 70 nm, and the maximum surface roughness Ra is 0.06. The fatigue limit of the modified composite surfaces obtained by the tensile fatigue test was 595.7 MPa, which was 85.7 MPa higher than the 510 MPa fatigue limit of the unmodified matrix, indicating that the method of composite surface modification can produce a deep deformation layer while maintaining good surface conditions. The results show that work hardening caused by a composite surface treatment is the most important factor for improving the fatigue performance of materials.
Revision of the Lichen Genus Phaeophyscia and Allied Atranorin Absent Taxa (Physciaceae) in South Korea
Authors: Liu Dong , Hur Jae-Seoun
Published: August 2019

The genus Phaeophyscia Moberg, which belongs to the family Physciaceae, includes about 50 species, with 17 species reported in South Korea. This genus is characterized by a foliose thallus, Physcia/Pachysporaria-type ascospores, a paraplectenchymatous-type lower cortex, and lacking atranorin. In this study, about 650 specimens of Phaeophyscia aligned with the atranorin-absent groups collected from South Korea were re-examined. The taxonomy of these groups in South Korea requires revision based on the analyses of the morphology, chemistry, and molecular phylogeny. We infer that (1) each genus of the main foliose groups of Physciaceae forms a monophyletic clade, which also supports the separation of Phaeophyscia species with a prosoplectenchymatous lower cortex into the genus Physciella; (2) three atranorin-lacking genera were confirmed in South Korea: Hyperphyscia, Phaeophyscia, and Physciella, including a new combination named Physciella poeltii (Frey) D. Liu and J.S. Hur, and three new records from South Korea of Phaeophyscia hunana, P. leana, and P. sonorae; and (3) four species should be excluded from the lichen flora of South Korea: Hyperphyscia adglutinata, Phaeophyscia endococcina, Phaeophyscia erythrocardia, and Phaeophyscia imbricata.
Lignan Glycosides from Urena lobata
Authors: Luo Yuan , Su Cong , Ding Ning , Qi Bowen , Jia Fangfang , Xu Xiping , Liu Xiao , Wang Juan , Wang Xiaohui , Tu Pengfei , Shi Shepo
Published: August 2019

Four new lignan glycosides; urenalignosides A–D (1–4), along with 12 known ones (5–16) were isolated from Urena lobata. Their structures were determined on the basis of extensive spectroscopic and spectrometric data (1D and 2D NMR; IR; CD; and HRESIMS). Compounds 2–4; 6; 7; 10; and 11 showed inhibition of nitric oxide production in lipopolysaccharide-induced RAW 264.7 macrophage cells with IC50 values in the range of 25.5–98.4 μM (positive control; quercetin; IC50 = 7.2 ± 0.2 μM).