bluuebunny/crossref_metadata_2025 huggingface dataset:
On-Line Monitoring of Blind Fastener Installation Process
Authors: Camacho Javier , Veiga Fernando , Penalva Mari Luz , Diez-Olivan Alberto , Deitert Lutz , López de Lacalle Norberto
Published: April 2019

Blind fasteners are of special interest for aircraft construction since they allow working on joints where only one side is accessible, as is the case in many common aerospace box-type structures, such as stabilizers and flaps. This paper aims to deliver an online monitoring method for the detection of incorrect installed blind fasteners. In this type of fastener, the back side of the assembly is not accessible, so monitoring the process installation is suitable as a system to assess the formed head at the back side with no access. The solution proposed consists of an on-line monitoring system that is based on sensor signals acquired during the installation. The signals are conveniently analyzed in order to provide an evaluation outcome on how the fastener was installed. This new method will help production to decrease/eliminate time and cost-intensive inspections and fasteners over installation in structures. The decrease of the number of installed fasteners will also contribute to weight savings and will reduce the use of resources.
Optical and Surface Properties of Monolithic Zirconia after Simulated Toothbrushing
Authors: Lee Jae-Hyun , Kim Sung-Hun , Han Jung-Suk , Yeo In-Sung Luke , Yoon Hyung-In
Published: April 2019

This in vitro study investigated the impact of various dentifrices on the shade, translucency, gloss, and surface characteristics of polishing- or glazing-finished monolithic zirconia surfaces after simulated toothbrushing. Eighty square-shaped monolithic zirconia specimens were divided into two major groups based on the finishing methods—polished (P) and glazed (G). Next, specimens from the two major groups were categorized into four subgroups: stored in distilled water (DW, control); brushed with a fluoride-free conventional dentifrice (C); brushed with a fluoride dentifrice (F); and brushed with a whitening dentifrice (W). Overall, eight groups were created—PDW, PC, PF, PW, GDW, GC, GF, and GW (n = 10 each). Shade, translucency, surface gloss, surface roughness, crystalline phase, and superficial topography data were obtained. Repeated-measures ANOVA and two-way ANOVA were used for intergroup comparison (all α = 0.05). The color differences (ΔE00) between pre- and posttreatment were 0.3158 (PDW), 0.7164 (PC), 0.7498 (PF), 0.8106 (PW), 0.1953 (GDW), 0.301 (GC), 0.3051 (GF), and 0.4846 (GW). A statistically significant difference was observed among the ΔE00, surface gloss, and surface roughness of monolithic zirconia. Thus, brushing with several dentifrices markedly affects the optical properties and surface characteristics of monolithic zirconia finished with polishing or glazing methods.
Effect of Heat Treatment on the Microstructure and Properties of a Ti3Al Linear Friction Welding Joint
Authors: Li Xiaohong , He Jianchao , Zhang Tiancang , Tao Jun , Li Ju , Zhang Yanhua
Published: April 2019

Heat treatment at different temperatures was carried out on a Ti3Al linear friction welding joint. The characteristics and evolution of the microstructure in the weld zone (WZ) and the thermo-mechanically affected zone (TMAZ) of the Ti3Al LFW joint were analyzed. Combined with the heat treatment after welding, the effect of the heat treatment temperature on the joint was discussed. The test results indicated that the linear friction welding (LFW) process can accomplish a reliable connection between Ti3Al alloys and the joint can avoid defects such as microcracks and voids. The weld zone of the as-welded Ti3Al alloy joint was mainly composed of metastable β phase, while the TMAZ was mainly composed of deformed α2 phase and metastable β phase. After being heat treated at different temperatures, the WZ of the Ti3Al LFW joint exhibited a significantly different microstructure. After heat treatment at 700 °C, dot-like structures precipitated and the joint microhardness increased significantly. Subsequently, the joint microhardness decreases with the increase in temperature. Under heat treatment at temperatures above 850 °C, the formed structure was acicular α2 phase and the joint microhardness after heat treatment was lower than that of the as-welded joint.
Rapid Immobilization of Simulated Radioactive Soil Waste Using Self-Propagating Synthesized Gd2Ti2O7 Pyrochlore Matrix
Authors: Xue Jiali , Zhang Kuibao , He Zongsheng , Zhao Wenwen , Li Weiwei , Xie Dayan , Luo Baozhu , Xu Kai , Zhang Haibin
Published: April 2019

A rapid and effective method is necessary in the disposal of severely radioactive contaminated soil waste. Simulated Ce-bearing radioactive soil waste was immobilized by self-propagating high-temperature synthesis (SHS) within 5 min in this study. The main work includes the rapid synthesis of soil waste forms, the analysis of phase composition, microstructure and chemical durability. These results show that the simulated nuclide Ce was successfully immobilized into the pyrochlore-rich waste matrice, whose main phases are SiO2, pyrochlore (Gd2Ti2O7) and Cu. The normalized leaching rates of Si and Na on the 42nd day are 1.86 × 10−3 and 1.63 × 10−2 g·m−2·d−1, respectively. And the normalized leaching rate of Ce also remains at low level (10−5–10−6 g·m−2·d−1) within 42 days.
Study of the Suitability of Different Types of Slag and Its Influence on the Quality of Green Grouts Obtained by Partial Replacement of Cement
Authors: Perez-Garcia Francisca , Parron-Rubio Maria Eugenia , Garcia-Manrique Jose Manuel , Rubio-Cintas Maria Dolores
Published: April 2019

This paper is part of a research line focused on the reduction of the use of cement in the industry. In this work, the study of work methodologies for the manufacture of green cementitious grout mixtures is studied. Grout is widely used in construction and it requires an important use of raw materials. On the other hand, the steel industry faces the problem of the growing generation of slag wastes due to the increase in steel manufacturing. The green grout aims to achieve the dual objective of reducing the demand for cement and improve the slag waste valorization. Slag is not introduced as an aggregate but through the direct replacement of cement and no additives. The research seeks a product where we can use steel slag intensively, guaranteeing minimum resistance and workability. Results with substitutions between a 25% to 50% and water/cement ratio of 1 are presented. In particular, the suitability of different slags (two Ladle Furnace Slag (LFS) and one Blast Furnace Slag (GGBS)) in the quality of the final product are analyzed. The feasibility of replacing cement with slag and the importance of the origin and pretreatment are highlighted.
Research on Internal Force Detection Method of Steel Bar in Elastic and Yielding Stage Based on Metal Magnetic Memory
Authors: Pang Caoyuan , Zhou Jianting , Zhao Ruiqiang , Ma Hu , Zhou Yi
Published: April 2019

Based on the metal magnetic memory effect, this paper proposed a new non-destructive testing method for the internal tensile force detection of steel bars by analyzing the self-magnetic flux leakage (SMFL) signals. The variation of the SMFL signal of the steel bar with the tensile force indicates that the curve of the SMFL signal has a significant extreme point when the tensile force reaches about 65% of the yield tension, of which the first derivative curve has extreme points in the elastic and yielding stages, respectively. To study the variation of SMFL signal with the axial position of the steel bar under different tensile forces, a parameter reflecting the fluctuation of the SMFL signal along the steel bar is proposed. The linear relationship between this parameter and the tensile force can be used to quantitatively calculate the tensile force of steel bar. The method in this paper provides significant application prospects for the internal force detection of steel bar in the actual engineering.
Toward a Fully Analytical Contact Resistance Expression in Organic Transistors
Authors: Kim Chang-Hyun , Horowitz Gilles
Published: April 2019

Contact resistance is a major characteristic of organic transistors, and its importance has received renewed attention due to the recent revelation of mobility overestimation. In this article, we propose a method to describe the contact resistance as a closed-form compact equation of the materials, interfaces, and geometrical parameters. The proposed model allows us to quantitatively understand the correlation between charge-injection and transport properties, while providing a tool for performance prediction and optimization. This theory is applied to a set of experimentally fabricated devices to exemplify how to utilize the model in practice.
A Multiscale Model of Oxidation Kinetics for Cu-Based Oxygen Carrier in Chemical Looping with Oxygen Uncoupling
Authors: Wang Hui , Li Zhenshan , Cai Ningsheng
Published: April 2019

Copper oxide is one of the promising oxygen carrier materials in chemical looping with oxygen uncoupling (CLOU) technology, cycling between Cu2O and CuO. In this study, a multiscale model was developed to describe the oxidation kinetics of the Cu-based oxygen carrier particle with oxygen, including surface, grain, and particle scale. It was considered that the solid product grows with the morphology of disperse islands on the grain surface, and O2 contacts with two different kinds of grain surfaces in the grain scale model, that is, Cu2O surface (solid reactant surface) and CuO surface (solid product surface). The two-stage behavior of the oxidation reaction of the Cu-based oxygen carrier was predicted successfully using the developed model, and the model results showed good agreement with experimental data in the literature. The effects of oxygen partial pressure, temperature, and particle structure on the oxidation performance were analyzed. The modeling results indicated that the transition of the conversion curve occurs when product islands cover most part of the grain surface. The oxygen partial pressure and particle structure have an obvious influence on the duration time of the fast reaction stage. Furthermore, the influence of the external mass transfer and the change of effectiveness factor during the oxidation reaction process were discussed to investigate the controlling step of the reaction. It was concluded that the external mass transfer step hardly affects the reaction performance under the particle sizes normally used in CLOU. The value of the effectiveness factor increases as the reaction goes by, which means the chemical reaction resistance at grain scale increases resulting from the growing number of product islands on the grain surface.
A Higher Order Chebyshev-Halley-Type Family of Iterative Methods for Multiple Roots
Authors: Behl Ramandeep , Martínez Eulalia , Cevallos Fabricio , Alarcón Diego
Published: April 2019

The aim of this paper is to introduce new high order iterative methods for multiple roots of the nonlinear scalar equation; this is a demanding task in the area of computational mathematics and numerical analysis. Specifically, we present a new Chebyshev–Halley-type iteration function having at least sixth-order convergence and eighth-order convergence for a particular value in the case of multiple roots. With regard to computational cost, each member of our scheme needs four functional evaluations each step. Therefore, the maximum efficiency index of our scheme is 1.6818 for α = 2 , which corresponds to an optimal method in the sense of Kung and Traub’s conjecture. We obtain the theoretical convergence order by using Taylor developments. Finally, we consider some real-life situations for establishing some numerical experiments to corroborate the theoretical results.
Early Blood Biomarkers to Improve Sepsis/Bacteremia Diagnostics in Pediatric Emergency Settings
Authors: Tamelytė Emilija , Vaičekauskienė Gineta , Dagys Algirdas , Lapinskas Tomas , Jankauskaitė Lina
Published: April 2019

Background: Sepsis is the leading cause of death in children worldwide. Early recognition and treatment are essential for preventing progression to lethal outcomes. CRP and Complete Blood Count (CBC) are the initial preferred tests to distinguish between bacterial and viral infections. Specific early diagnostic markers are still missing. Aim: To investigate diagnostic value of Neutrophil–Lymphocyte Ratio (NLR), Mean Platelet Volume (MPV) and Platelet–MPV ratio (PLT/MPV) to distinguish sepsis/bacteremia and viral infection. Methods: We conducted a retrospective data analysis of case records of 115 children from 1 month to 5 years of age. All cases were divided into two groups—sepsis/bacteremia (n = 68) and viral (n = 47) patients, and further subdivided according to the time of arrival into early or late (≤12 or 12–48 h post the onset of fever, respectively). Analysis of CBC and CRP results was performed. NLR and PLT/MPV were calculated. Results: Sepsis/bacteremia group demonstrated higher absolute platelets count (370.15 ± 134.65 × 109/L versus 288.91 ± 107.14 × 109/L; p = 0.001), NLR (2.69 ± 2.03 versus 1.83 ± 1.70; p = 0.006), and PLT/MPV (41.42 ± 15.86 versus 33.45 ± 17.97; p = 0.001). PLT/MPV was increased in early arrival sepsis/bacteremia infants (42.70 ± 8.57 versus 31.01 ± 8.21; p = 0.008). NLR and MPV were significantly lower in infants (≤12 months) with viral infection on late arrival (1.16 ± 1.06 versus 1.90 ± 1.25, p = 0.025 for NLR and 8.94 ± 0.95fl versus 9.44 ± 0.85fl, p = 0.046 for MPV). Conclusion: Together with standard blood biomarkers, such as CRP, neutrophils, or platelets count, PLT/MPV is a promising biomarker for clinical practice to help discriminate between viral disease or sepsis/bacteremia in all children, especially in early onset of symptoms. NLR and MPV could support exclusion of sepsis/bacteremia in late arrival cases.
Novel Polymeric Thin-Film Composite Membranes for High-Temperature Gas Separations
Authors: Weigelt Fynn , Escorihuela Sara , Descalzo Alberto , Tena Alberto , Escolástico Sonia , Shishatskiy Sergey , Serra Jose Manuel , Brinkmann Torsten
Published: April 2019

Novel selective polymeric thin-film composite membranes (TFCMs) for applications at elevated temperatures were developed. Thin selective layers of the polyimides Matrimid 5218® and 6FDA-6FpDA were cast on a developed polybenzimidazole (PBI) porous support prepared by a phase inversion process. The TFCM properties were investigated with different gases in a wide temperature range, including temperatures up to 270 °C. The membranes showed very high thermal stability and performed well at the elevated temperatures. The development of highly thermally resistant polymeric membranes such as these TFCMs opens opportunities for application in high-temperature integrated processes, such as catalytic membrane reactors for the water-gas shift reaction in order to maximize H2 yield.
Net Shape Extrusion of Titanium Bars through Coupled two Part Preform Manufacturing Process: System of Systems Approach—Part II
Authors: Stroud Adam , Ertas Atila
Published: April 2019

The first part of this paper explored the identification of various methodological challenges which have to be addressed when designing complex multi-system integration associated with titanium metalworking and manufacture, while in this second part of the paper, we explore the evolution of System of Systems (SoS) design and development of complex multi-system integration. Theory of Inventive Problem Solving (TRIZ) is employed to address identified system incongruity. The utilization of the SoS design approach coupled with the TRIZ innovation technique proved effective at addressing the system constraints for the titanium manufacturing supply chain. The utilization of the two-part process prescribed by the SoS design approach proved effective at addressing requirements and broadly stated industry needs. Through this unique system, design net-shaped structural beam from common aerospace grade titanium (Ti-6Al-4V) was successfully manufactured.
Understanding Mechanical Properties of Nano-Grained Bainitic Steels from Multiscale Structural Analysis
Authors: Caballero Francisca G. , Rementeria Rosalia , Morales-Rivas Lucia , Benito-Alfonso Miguel , Yang Jer-Ren , de Castro David , Poplawsky Jonathan D. , Sourmail Thomas , Garcia-Mateo Carlos
Published: April 2019

Steel components working in extreme conditions require materials presenting the highest performances. Nowadays, nanoengineering is being applied to the development of ultra-high strength steels as a key-enabling technology in the steel sector. The present article describes the multiscale structure of nano-grained steels designed using atomic transformation theory and processed by a simple heat treatment. Outstanding mechanical properties for these novel steels are reported, and strain-hardening mechanisms are discussed.
Extraction of Rare Earth Elements from Chloride Media with Tetrabutyl Diglycolamide in 1-Octanol Modified Carbon Dioxide
Authors: Case Mary , Fox Robert , Baek Donna , Wai Chien
Published: April 2019

Rare earth elements (REEs) are critical to our modern world. Recycling REEs from used products could help with potential supply issues. Extracting REEs from chloride media with tetrabutyl diglycolamide (TBDGA) in carbon dioxide could help recycle REEs with less waste than traditional solvents. Carbon dioxide as a solvent is inexpensive, inert, and reusable. Conditions for extraction of Eu from aqueous chloride media were optimized by varying moles percent of 1-octanol modifier, temperature, pressure, Eu concentration, TBDGA concentration, Cl− concentration, and HCl concentration. These optimized conditions were tested on a Y, Ce, Eu, Tb simulant material, REEs containing NdFeB magnets, and lighting phosphor material. The optimized conditions were found to be 23 °C, 24.1 MPa, 0.5 mol% 1-octanol, with an excess of TBDGA. At these conditions 95 ± 2% Eu was extracted from 8 M (mol/m3) HCl. Extraction from the mixed REE simulate material resulted in separation of Y, Eu, and Tb from the Ce which remained in the aqueous solution. The extraction on NdFeB magnet dissolved into 8 M HCl resulted in extraction of Pr, Nd, Dy, and Fe >97%. This results in a separation from B, Al, and Ni. Extraction from a trichromatic lighting phosphor leachate resulted in extraction of Y and Eu >93% and no extraction of Ba, Mg, and Al.
Enhancement of Light Extraction Efficiency for InGaN/GaN Light-Emitting Diodes Using Silver Nanoparticle Embedded ZnO Thin Films
Authors: Lei Po-Hsun , Yang Chyi-Da , Huang Po-Chun , Yeh Sheng-Jhan
Published: April 2019

In this study, we propose a liquid-phase-deposited silver nanoparticle embedded ZnO (LPD-Ag NP/ZnO) thin film at room temperature to improve the light extraction efficiency (LEE) for InGaN/GaN light-emitting diodes (LEDs). The treatment solution for the deposition of the LPD-Ag/NP ZnO thin film comprised a ZnO-powder-saturated HCl and a silver nitrate (AgNO3) aqueous solution. The enhanced LEE of an InGaN/GaN LED with the LPD-Ag NP/ZnO window layer can be attributed to the surface texture and localized surface plasmon (LSP) coupling effect. The surface texture of the LPD-Ag/NP ZnO window layer relies on the AgNO3 concentration, which decides the root-mean-square (RMS) roughness of the thin film. The LSP resonance or extinction wavelength also depends on the concentration of AgNO3, which determines the Ag NP size and content of Ag atoms in the LPD-Ag NP/ZnO thin film. The AgNO3 concentration for the optimal LEE of an InGaN/GaN LED with an LPD-Ag NP/ZnO window layer occurs at 0.05 M, which demonstrates an increased light output intensity that is approximately 1.52 times that of a conventional InGaN/GaN LED under a 20-mA driving current.
Antioxidant Activity, and Volatile and Phytosterol Contents of Strobilanthes crispus Dehydrated Using Conventional and Vacuum Microwave Drying Methods
Authors: Chua Lisa Yen Wen , Chua Bee Lin , Figiel Adam , Chong Chien Hwa , Wojdyło Aneta , Szumny Antoni , Choong Thomas Shean Yaw
Published: April 2019

The preservation of active constituents in fresh herbs is affected by drying methods. An effective drying method for Strobilanthes crispus which is increasingly marketed as an important herbal tea remains to be reported. This study evaluated the effects of conventional and new drying technologies, namely vacuum microwave drying methods, on the antioxidant activity and yield of essential oil volatiles and phytosterols. These drying methods included convective drying (CD) at 40 °C, 50 °C, and 60 °C; vacuum microwave drying (VMD) at 6, 9, and 12 W/g; convective pre-drying and vacuum microwave finish drying (CPD-VMFD) at 50 °C and 9 W/g; and freeze-drying (FD). GC–MS revealed 33 volatiles, and 2-hexen-1-ol, 2-hexenal, 1-octen-3-ol, linalool, and benzaldehyde were major constituents. The compounds β-sitosterol and α-linolenic acid were the most abundant phytosterol and fatty acid, respectively, in fresh S. crispus. The highest phenolic content was achieved with CD at 60 °C. The highest antioxidant activity was obtained with CD at 40 °C and VMD at 9 W/g. On the contrary, the highest total volatiles and phytosterols were detected with CD at 50 °C and VMD at 9 W/g, respectively. This study showed that CD and VMD were effective in producing highly bioactive S. crispus. A suitable drying parameter level, irrespective of the drying method used, was an important influencing factor.
Tests on Material Compatibility of Phase Change Materials and Selected Plastics
Authors: Ostrý Milan , Bantová Sylva , Struhala Karel
Published: April 2019

Practical applications of Phase Change Materials (PCMs) often require their encapsulation in other materials, such as metals or plastics. This raises the issue of compatibility between PCMs and encapsulating materials, which has still not been sufficiently addressed. The study presented here follows existing research and provides experimental evaluation of the suitability of selected PCMs for proposed integration in building structures. Two organic PCMs, two inorganic PCMs and three representative plastics (polypropylene (PP-H), high density polyethylene (PE-HD) and polyvinylchloride (PVC-U)) were selected for compatibility tests. Evaluation of the results is based on the mass variations of the plastic samples during the test period. Plastic samples were immersed in PCMs and subjected to periodic heating and cooling (for 16 weeks) in a small environmental chamber simulating real operational conditions. The results show that the organic PCMs have a greater ability to penetrate the PE-HD and PP-H compared with the inorganic PCMs. The penetration of all PCMs was most notable during the first four weeks of the experiment. Later it slowed down significantly. Overall, the mass changes in PE-HD and PP-H samples did not exceed 6.9% when immersed in organic PCMs and 1.8% in inorganic PCMs. PVC-U samples exhibited almost negligible (less than 0.1%) mass variation in all cases.
Biomimetic Mineralization of Magnetic Iron Oxide Nanoparticles Mediated by Bi-Functional Copolypeptides
Authors: Liu Liu , Pu Ximing , Yin Guangfu , Chen Xianchun , Yin Jie , Wu Yuhao
Published: April 2019

Magnetite (Fe3O4) nanoparticles are widely used in multiple biomedical applications due to their magnetic properties depending on the size, shape and organization of the crystals. However, the crystal growth and morphology of Fe3O4 nanoparticles remain difficult to control without using organic solvent or a high temperature. Inspired by the natural biomineralization process, a 14-mer bi-functional copolypeptide, leveraging the affinity of binding Fe3O4 together with targeting ovarian cancer cell A2780, was used as a template in the biomimetic mineralization of magnetite. Alongside this, a ginger extract was applied as an antioxidant and a size-conditioning agent of Fe3O4 crystals. As a result of the cooperative effects of the peptide and the ginger extract, the size and dispersibility of Fe3O4 were controlled based on the interaction of the amino acid and the ginger extract. Our study also demonstrated that the obtained particles with superparamagnetism could selectively be taken up by A2780 cells. In summary, the Fe3O4-QY-G nanoparticles may have potential applications in targeting tumor therapy or angiography.
Distinct Difference in Sensitivity of NIR vs. IR Bands of Melamine to Inter-Molecular Interactions with Impact on Analytical Spectroscopy Explained by Anharmonic Quantum Mechanical Study
Authors: Grabska Justyna , Beć Krzysztof B. , Kirchler Christian G. , Ozaki Yukihiro , Huck Christian W.
Published: April 2019

Melamine (IUPAC: 1,3,5-Triazine-2,4,6-triamine) attracts high attention in analytical vibrational spectroscopy due to its misuse as a food adulterant. Vibrational spectroscopy [infrared (IR) and Raman and near-infrared (NIR) spectroscopy] is a major quality control tool in the detection and quantification of melamine content. The physical background for the measured spectra is not interpreted in analytical spectroscopy using chemometrics. In contrast, quantum mechanical calculations are capable of providing deep and independent insights therein. So far, the NIR region of crystalline melamine has not been studied by quantum mechanical calculations, while the investigations of its IR spectra have remained limited. In the present work, we employed fully anharmonic calculation of the NIR spectrum of melamine based on finite models, and also performed IR spectral simulation by using an infinite crystal model—periodic in three dimensions. This yielded detailed and unambiguous NIR band assignments and revised the previously known IR band assignments. We found that the out-of-plane fundamental transitions, which are essential in the IR region, are markedly more sensitive to out-of-plane inter-molecular interactions of melamine than NIR transitions. Proper description of the chemical surrounding of the molecule of melamine is more important than the anharmonicity of its vibrations. In contrast, the NIR bands mostly arise from in-plane vibrations, and remain surprisingly insensitive to the chemical environment. These findings explain previous observations that were reported in IR and NIR analytical studies of melamine.
Rhinoclactones A-E, Resorcylic Acid Analogs from Desert Plant Endophytic Fungus Rhinocladiella similis
Authors: Li Luying , Zhang Xiaoyan , Tan Xiangmei , Sun Bingda , Wu Bin , Yu Meng , Zhang Tao , Zhang Yonggang , Ding Gang
Published: April 2019

Seven resorcylic acid lactones (RALs) including five new analog rhinoclactones, A–E (1, 2, 4–6), were isolated from an endophytic fungus Rhinocladiella similis in the plant Agriophyllum squarrosum collected from the Tengger Desert of the Ningxia Province, China. The structures of these new compounds were determined by HR-ESI-MS (High Resolution Electrospray Ionization Mass Spectrometry), NMR data, modified Mosher’s method, and X-ray diffraction experiments. All compounds isolated from this fungus possessed the 16-OMe/14-OH, not the common 16-OH/14-OH or 16-OH/14-OMe groups on the aromatic ring, which are rarely found in nature. Compound 7 displayed cytotoxic activities against HCT116 and HeLa cancer cell lines. The possible biosynthesis of 1–7 is suggested, and the potential ecological roles of these fungal secondary metabolites is discussed.
Traceless Solid-Phase Synthesis of Ketones via Acid-Labile Enol Ethers: Application in the Synthesis of Natural Products and Derivatives
Authors: Schütznerová Eva , Krchňáková Anna , Krchňák Viktor
Published: April 2019

In solid-phase organic synthesis, Wang resin is traditionally used for the immobilization of acids, alcohols, phenols, and amines. We report the use of Wang resin for the traceless synthesis of ketones via acid-labile enol ethers. We demonstrate the practicality of this synthetic strategy on the solid-phase synthesis of pyrrolidine-2,4-diones, which represent the core structure of several natural products, including tetramic acid. Base-triggered condensation of pyrrolidine-2,4-diones yielded 4-hydroxy-1,1′,2′,5-tetrahydro-2H,5′H-[3,3′-bipyrrole]-2,5′-diones.
Solvent Fractionation and Acetone Precipitation for Crude Saponins from Eurycoma longifolia Extract
Authors: Chua Lee Suan , Lau Cher Haan , Chew Chee Yung , Dawood Dawood Ali Salim
Published: April 2019

Eurycoma longifolia is a popular folk medicine in South East Asia. This study was focused on saccharide-containing compounds including saponins, mainly because of their medical potentials. Different organic solvents such as ethyl acetate, butanol, and chloroform were used to fractionate the phytochemical groups, which were consequently precipitated in cold acetone. Solvent fractionation was found to increase the total saponin content based on colorimetric assay using vanillin and sulfuric acid. Ethyl acetate fraction and its precipitate were showed to have the highest crude saponins after acetone precipitation. The samples were shown to have anti-proliferative activity comparable with tamoxifen (IC50 = 110.6 µg/mL) against human breast cancer cells. The anti-proliferative activities of the samples were significantly improved from crude extract (IC50 = 616.3 µg/mL) to ethyl acetate fraction (IC50 = 185.4 µg/mL) and its precipitate (IC50 = 153.4 µg/mL). LC-DAD-MS/MS analysis revealed that the saccharide-containing compounds such as m/z 497, 610, 723, 836, and 949 were abundant in the samples, and they could be ionized in negative ion mode. The compounds consisted of 226 amu monomers with UV-absorbing property at 254 nm, and were tentatively identified as formylated hexoses. To conclude, solvent fractionation and acetone precipitation could produce saccharide-containing compounds including saponins with higher anti-proliferative activity than crude extract against MCF-7 cells. This is the first study to use non-toxic solvents for fractionation of bioactive compounds from highly complex plant extract of E. longifolia.
Exploring the Development Requirements for Virtual Reality Gait Analysis
Authors: Khan Mohammed Soheeb , Charissis Vassilis , Sakellariou Sophia
Published: April 2019

The hip joint is highly prone to traumatic and degenerative pathologies resulting in irregular locomotion. Monitoring and treatment depend on high-end technology facilities requiring physician and patient co-location, thus limiting access to specialist monitoring and treatment for populations living in rural and remote locations. Telemedicine offers an alternative means of monitoring, negating the need for patient physical presence. In addition, emerging technologies, such as virtual reality (VR) and immersive technologies, offer potential future solutions through virtual presence, where the patient and health professional can meet in a virtual environment (a virtual clinic). To this end, a prototype asynchronous telemedicine VR gait analysis system was designed, aiming to transfer a full clinical facility within the patients’ local proximity. The proposed system employs cost-effective alternative motion capture combined with the system’s immersive 3D virtual gait analysis clinic. The user interface and the tools in the application offer health professionals asynchronous, objective, and subjective analyses. This paper investigates the requirements for the design of such a system and discusses preliminary comparative data of its performance evaluation against a high-fidelity gait analysis clinical application.
TiO2 Nanostructures for Photoelectrocatalytic Degradation of Acetaminophen
Authors: Borràs-Ferrís Joan , Sánchez-Tovar Rita , Blasco-Tamarit Encarnación , Muñoz-Portero Maria José , Fernández-Domene Ramón M. , García-Antón José
Published: April 2019

Advanced oxidation processes driven by renewable energy sources are gaining attention in degrading organic pollutants in waste waters in an efficient and sustainable way. The present work is focused on a study of TiO2 nanotubes as photocatalysts for photoelectrocatalytic (PEC) degradation of acetaminophen (AMP) at different pH (3, 7, and 9). In particular, different TiO2 photocatalysts were synthetized by stirring the electrode at different Reynolds numbers (Res) during electrochemical anodization. The morphology of the photocatalysts and their crystalline structure were evaluated by field emission scanning electron microscopy (FESEM) and Raman confocal laser microscopy (RCLM). These analyses revealed that anatase TiO2 nanotubes were obtained after anodization. In addition, photocurrent densities versus potential curves were performed in order to characterize the electrochemical properties of the photocatalysts. These results showed that increasing the Re during anodization led to an enhancement in the obtained photocurrents, since under hydrodynamic conditions part of the initiation layer formed over the tubes was removed. PEC degradation of acetaminophen was followed by ultraviolet-visible absorbance measurements and chemical oxygen demand tests. As drug mineralization was the most important issue, total organic carbon measurements were also carried out. The statistical significance analysis established that acetaminophen PEC degradation improved as hydrodynamic conditions linearly increased in the studied range (Re from 0 to 600). Additionally, acetaminophen conversion had a quadratic behavior with respect to the reaction pH, where the maximum conversion value was reached at pH 3. However, in this case, the diversity of the byproducts increased due to a different PEC degradation mechanism.
A Microfluidic Chip Embracing a Nanofiber Scaffold for 3D Cell Culture and Real-Time Monitoring
Authors: Kim Jeong Hwa , Park Ju Young , Jin Songwan , Yoon Sik , Kwak Jong-Young , Jeong Young Hun
Published: April 2019

Recently, three-dimensional (3D) cell culture and tissue-on-a-chip application have attracted attention because of increasing demand from the industries and their potential to replace conventional two-dimensional culture and animal tests. As a result, numerous studies on 3D in-vitro cell culture and microfluidic chip have been conducted. In this study, a microfluidic chip embracing a nanofiber scaffold is presented. A electrospun nanofiber scaffold can provide 3D cell culture conditions to a microfluidic chip environment, and its perfusion method in the chip can allow real-time monitoring of cell status based on the conditioned culture medium. To justify the applicability of the developed chip to 3D cell culture and real-time monitoring, HepG2 cells were cultured in the chip for 14 days. Results demonstrated that the cells were successfully cultured with 3D culture-specific-morphology in the chip, and their albumin and alpha-fetoprotein production was monitored in real-time for 14 days.
Sesbania Gum-Supported Hydrophilic Electrospun Fibers Containing Nanosilver with Superior Antibacterial Activity
Authors: Lan Shi , Lu Yaning , Li Chun , Zhao Shuang , Liu Naren , Sheng Xianliang
Published: April 2019

In this contribution, we report for the first time on a new strategy for developing sesbania gum-supported hydrophilic fibers containing nanosilver using electrospinning (SG-Ag/PAN electrospun fibers), which gives the fibers superior antibacterial activity. Employing a series of advanced technologies—scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, UV–visible absorption spectroscopy, X-ray photoelectron spectroscopy, and contact angle testing—we characterized the as-synthesized SG-Ag/PAN electrospun fibers in terms of morphology, size, surface state, chemical composition, and hydrophilicity. By adjusting the synthesis conditions, in particular the feed ratio of sesbania gum (SG) and polyacrylonitrile (PAN) to Ag nanoparticles (NPs), we regulated the morphology and size of the as-electrospun fibers. The fibers’ antibacterial properties were examined using the colony-counting method with two model bacteria: Escherichia coli (a Gram-negative bacterium) and Staphylococcus aureus (a Gram-positive bacterium). Interestingly, compared to Ag/PAN and SG-PAN electrospun fibers, the final SG-Ag/PAN showed enhanced antibacterial activity towards both of the model bacteria due to the combination of antibacterial Ag NPs and hydrophilic SG, which enabled the fibers to have sufficient contact with the bacteria. We believe this strategy has great potential for applications in antibacterial-related fields.
Adherence to DASH-Style Dietary Pattern Impacts on Adiponectin and Clustered Metabolic Risk in Older Women
Authors: Nilsson Andreas , Halvardsson Patrik , Kadi Fawzi
Published: April 2019

While dietary patterns are related to the age-related progression of chronic diseases, to what extent different dietary patterns influence inflammatory and metabolic risk factors in older adults remains to be elucidated. Additionally, potential moderating effects by physical activity (PA) become important to clarify. Here, we hypothesize that dietary patterns are linked to inflammatory and metabolic biomarkers and that these links are independent of PA. The present study aims to explore links between two dietary constructs and biomarkers of systemic inflammation and metabolic health in older women, while considering time spent in moderate-to-vigorous PA (MVPA). A cross-sectional analysis of a sample of 112 community-dwelling older women (65–70 years old) was performed. Dietary constructs based on the Dietary Approach to Stop Hypertension (DASH) and the dietary inflammatory index (DII) were determined from food records. MVPA was objectively assessed using accelerometry. Metabolic outcomes (waist circumference, systolic/diastolic blood pressures and levels of glucose, triglycerides and high-density lipoprotein (HDL)-cholesterol) and inflammatory biomarkers (C-reactive protein (CRP), fibrinogen and adiponectin) were determined using standardized procedures and a clustered metabolic risk score was derived. Adherence to DASH-style diet was significantly (p < 0.05) associated with a lower clustered metabolic risk, where women in the highest adherence group had a significantly (p < 0.05) lower waist circumference and blood glucose level compared to those in the lowest group. Further, a significantly higher (p < 0.05) adiponectin level was observed in the high DASH adherence group compared to those with low adherence. Notably, adjustment by waist circumference did not alter links with either adiponectin or blood glucose level. Importantly, all observed links remained significant after further adjustment for time in MVPA. Finally, no significant associations were observed when the dietary pattern was defined by the DII. The findings of this study demonstrate that DASH-style diets promote a systemic anti-inflammatory environment, while also mitigating clustered metabolic risk in older women. A key finding is that favourable impacts of the DASH-style diet are independent of time spent in moderate-to-vigorous PA, which further strengthens healthy eating behaviours as a key target for clinical and public health interventions designed to prevent age-related metabolic abnormalities.
The Challenge of Managing Undernutrition in Older People with Frailty
Authors: Roberts Helen C. , Lim Stephen E. R. , Cox Natalie J. , Ibrahim Kinda
Published: April 2019

Many older people with frailty are at risk of malnutrition and poor health, yet there is evidence that improving nutrition and weight loss can reduce frailty. This will become more important as the number of older people with frailty increases worldwide in future. Identifying those at risk is challenging due to the difficulty of reaching and screening those older people most at risk, the large number of nutritional assessment tools used, and the lack of consensus on the criteria to make a diagnosis of malnutrition. The management of older people with or at risk of malnutrition should be multi-modal and multi-disciplinary, and all care staff have an important role in delivering appropriate nutritional advice and support. This paper will highlight a number of practical approaches that clinicians can take to manage malnutrition in older people with frailty in community and acute settings, including environmental changes to enhance mealtime experience, food fortification and supplementation.
Potential Protective Mechanisms of Ketone Bodies in Migraine Prevention
Authors: Gross Elena C. , Klement Rainer J. , Schoenen Jean , D’Agostino Dominic P. , Fischer Dirk
Published: April 2019

An increasing amount of evidence suggests that migraines are a response to a cerebral energy deficiency or oxidative stress levels that exceed antioxidant capacity. The ketogenic diet (KD), a diet mimicking fasting that leads to the elevation of ketone bodies (KBs), is a therapeutic intervention targeting cerebral metabolism that has recently shown great promise in the prevention of migraines. KBs are an alternative fuel source for the brain, and are thus likely able to circumvent some of the abnormalities in glucose metabolism and transport found in migraines. Recent research has shown that KBs—D-β-hydroxybutyrate in particular—are more than metabolites. As signalling molecules, they have the potential to positively influence other pathways commonly believed to be part of migraine pathophysiology, namely: mitochondrial functioning, oxidative stress, cerebral excitability, inflammation and the gut microbiome. This review will describe the mechanisms by which the presence of KBs, D-BHB in particular, could influence those migraine pathophysiological mechanisms. To this end, common abnormalities in migraines are summarised with a particular focus on clinical data, including phenotypic, biochemical, genetic and therapeutic studies. Experimental animal data will be discussed to elaborate on the potential therapeutic mechanisms of elevated KBs in migraine pathophysiology, with a particular focus on the actions of D-BHB. In complex diseases such as migraines, a therapy that can target multiple possible pathogenic pathways seems advantageous. Further research is needed to establish whether the absence/restriction of dietary carbohydrates, the presence of KBs, or both, are of primary importance for the migraine protective effects of the KD.
Effect of Dietary Incorporation of Linseed Alone or Together with Tomato-Red Pepper Mix on Laying Hens’ Egg Yolk Fatty Acids Profile and Health Lipid Indexes
Authors: Omri Besma , Chalghoumi Raja , Izzo Luana , Ritieni Alberto , Lucarini Massimo , Durazzo Alessandra , Abdouli Hédi , Santini Antonello
Published: April 2019

This study evaluated the effect of linseed incorporation in laying hens’ feed (alone or along with a tomato-red pepper mix) on laying hens’ egg yolk fatty acids profile, as well as on their atherogenic (IA) and thrombogenic (IT) health lipid indexes, and the ratio between the hypocholesterolemic and hypercholesterolemic fatty acids (HH). Sixty 27 weeks-old Novogen White laying hens were divided into three groups and given 100 g/hen/day of a standard diet (Control, C) containing 4.5% of ground linseed (Linseed diet, L), containing 1% of dried tomato paste and 1% sweet red pepper (Lineseeds-Tomato-Pepper, LTP). The linseed dietary inclusion significantly reduced the egg yolk content of palmitic acid from 25.41% (C) to 23.43% (L) and that of stearic acid from 14.75% (C) to 12.52% (L). Feeding 4.5% ground linseed did not affect the egg yolk content of α-Linolenic acid but significantly increased the egg yolk concentration of eicosapentaenoic acid (EPA) from 0.011% (C) to 0.047% (L) and that of docosahexaenoic acid (DHA) from 1.94% (C) to 2.73% (L). The IA and the HH were not affected (p > 0.05) by the dietary addition of linseed, whereas the IT decreased (p < 0.05) from 1.16 (C) to 0.86 (L). Adding tomato-sweet red pepper mix to the linseed-supplemented feed did not affect the measured parameters as compared to the linseed dietary treatment.
Refractive Index Sensor Based on Twisted Tapered Plastic Optical Fibers
Authors: Teng Chuanxin , Deng Hongchang , Liu Houquan , Yang Hongyan , Yuan Libo , Zheng Jie , Deng Shijie
Published: April 2019

We proposed a refractive index (RI) sensor employing two twisted tapered plastic optical fibers (POFs). The tapered POFs were fabricated by a heating and drawing method and were twisted around each other to form a coupled structure. The sensor consisted of two input ports, a twisted region, and two output ports. The tapered POF could make the light couple from one POF to the other easily. The twisted tapered POFs could constitute a self-referencing sensor, and by monitoring the changes of the coupling ratio, the variations of the external medium RIs could be measured. The RI sensing performances for the sensors with different fiber diameters and twisted region lengths were studied. The sensitivities of 1700%/RIU and −3496%/RIU in the RI ranges of 1.37–1.41 and 1.41–1.44 were obtained, respectively. The sensor is a low-cost solution for liquid RI measurement, which has the features of simple structure and easy fabrication.
Computing the Double-Gyroaverage Term Incorporating Short-Scale Perturbation and Steep Equilibrium Profile by the Interpolation Algorithm
Authors: Zhang Shuangxi , Mehrenberger Michel , Steiner Christophe
Published: April 2019

In the gyrokinetic model and simulations, when the double-gyroaverage term incorporates the combining effect contributed by the finite Larmor radius, short scales of the perturbation, and steep gradient of the equilibrium profile, the low-order approximation of this term could generate unignorable error. This paper implements an interpolation algorithm to compute the double-gyroaverage term without low-order approximation to avoid this error. For a steep equilibrium density, the obvious difference between the density on the gyrocenter coordinate frame and the one on the particle coordinate frame should be accounted for in the quasi-neutrality equation. A Euler–Maclaurin-based quadrature integrating algorithm is developed to compute the quadrature integral for the distribution of the magnetic moment. The application of the interpolation algorithm to computing the double-gyroaverage term and to solving the quasi-neutrality equation is benchmarked by comparing the numerical results with the known analytical solutions. Finally, to take advantage of the interpolation solver clearer, the numerical comparison between the interpolation solver and a classical second order solver is carried out in a constant theta-pinch magnetic field configuration using SELALIB code. When the equilibrium profile is not steep and the perturbation only has the non-zero mode number along the parallel spatial dimension, the results computed by the two solvers match each other well. When the gradient of the equilibrium profile is steep, the interpolation solver provides a bigger driving effect for the ion-temperature-gradient modes, which possess large polar mode numbers.
Glass Transition in Crosslinked Nanocomposite Scaffolds of Gelatin/Chitosan/Hydroxyapatite
Authors: Catalan Karina N. , Corrales Tomas P. , Forero Juan C. , Romero Christian P. , Acevedo Cristian A.
Published: April 2019

The development of biopolymeric scaffolds crosslinked with nanoparticles is an emerging field. Gelatin/chitosan scaffolds are gaining interest in medical areas, e.g., bone tissue engineering, given their suitability for nano-hydroxyapatite incorporation. The glass transition temperature is a thermodynamic property of polymer scaffolds that changes with crosslinker or nanofiller concentration. Here, we report the experimental change in glass transition temperature of gelatin/chitosan scaffolds modified by hydroxyapatite nanoparticles and crosslinker concentration. Our results show synergic effects between nanoparticles and crosslinking, which leads to a non-linear behavior of the glass transition temperature. Furthermore, a theoretical model to predict glass transition is proposed. This model can be used as a mathematical tool for the design of future scaffolds used in bone tissue engineering.