bluuebunny/crossref_metadata_2025 huggingface dataset:
A Retrospective Analysis of the Cartilage Kunitz Protease Inhibitory Proteins Identifies These as Members of the Inter-α-Trypsin Inhibitor Superfamily with Potential Roles in the Protection of the Articulatory Surface
Authors: Smith Susan M. , Melrose James
Published: January 2019

Aim: The aim of this study was to assess if the ovine articular cartilage serine proteinase inhibitors (SPIs) were related to the Kunitz inter-α-trypsin inhibitor (ITI) family. Methods: Ovine articular cartilage was finely diced and extracted in 6 M urea and SPIs isolated by sequential anion exchange, HA affinity and Sephadex G100 gel permeation chromatography. Selected samples were also subjected to chymotrypsin and concanavalin-A affinity chromatography. Eluant fractions from these isolation steps were monitored for protein and trypsin inhibitory activity. Inhibitory fractions were assessed by affinity blotting using biotinylated trypsin to detect SPIs and by Western blotting using antibodies to α1-microglobulin, bikunin, TSG-6 and 2-B-6 (+) CS epitope generated by chondroitinase-ABC digestion. Results: 2-B-6 (+) positive 250, 220,120, 58 and 36 kDa SPIs were detected. The 58 kDa SPI contained α1-microglobulin, bikunin and chondroitin-4-sulfate stub epitope consistent with an identity of α1-microglobulin-bikunin (AMBP) precursor and was also isolated by concanavalin-A lectin affinity chromatography indicating it had N-glycosylation. Kunitz protease inhibitor (KPI) species of 36, 26, 12 and 6 kDa were autolytically generated by prolonged storage of the 120 and 58 kDa SPIs; chymotrypsin affinity chromatography generated the 6 kDa SPI. KPI domain 1 and 2 SPIs were separated by concanavalin lectin affinity chromatography, domain 1 displayed affinity for this lectin indicating it had N-glycosylation. KPI 1 and 2 displayed potent inhibitory activity against trypsin, chymotrypsin, kallikrein, leucocyte elastase and cathepsin G. Localisation of versican, lubricin and hyaluronan (HA) in the surface regions of articular cartilage represented probable binding sites for the ITI serine proteinase inhibitors (SPIs) which may preserve articulatory properties and joint function. Discussion/Conclusions: The Kunitz SPI proteins synthesised by articular chondrocytes are members of the ITI superfamily. By analogy with other tissues in which these proteins occur we deduce that the cartilage Kunitz SPIs may be multifunctional proteins. Binding of the cartilage Kunitz SPIs to HA may protect this polymer from depolymerisation by free radical damage and may also protect other components in the cartilage surface from proteolytic degradation preserving joint function.
Sensory Neuropeptides and their Receptors Participate in Mechano-Regulation of Murine Macrophages
Authors: Muschter Dominique , Beiderbeck Anna-Sophie , Späth Tanja , Kirschneck Christian , Schröder Agnes , Grässel Susanne
Published: January 2019

This study aimed to analyze if the sensory neuropeptide SP (SP) and the neurokinin receptor 1 (NK1R) are involved in macrophage mechano-transduction, similar to chondrocytes, and if alpha-calcitonin gene-related peptide (αCGRP) and the CGRP receptor (CRLR/Ramp1) show comparable activity. Murine RAW264.7 macrophages were subjected to a cyclic stretch for 1–3 days and 4 h/day. Loading and neuropeptide effects were analyzed for gene and protein expression of neuropeptides and their receptors, adhesion, apoptosis, proliferation and ROS activity. Murine bone marrow-derived macrophages (BMM) were isolated after surgical osteoarthritis (OA) induction and proliferation, apoptosis and osteoclastogenesis were analyzed in response to loading. Loading induced NK1R and CRLR/Ramp1 gene expression and altered protein expression in RAW264.7 macrophages. SP protein and mRNA level decreased after loading whereas αCGRP mRNA expression was stabilized. SP reduced adhesion in loaded RAW264.7 macrophages and both neuropeptides initially increased the ROS activity followed by a time-dependent suppression. OA induction sensitized BMM to caspase 3/7 mediated apoptosis after loading. Both sensory neuropeptides, SP and αCGRP, and their receptors are involved in murine macrophage mechano-transduction affecting neuropeptide impact on adhesion and ROS activity. OA induction altered BMM apoptosis in response to loading indicate that OA-associated biomechanical alterations might affect the macrophage population.
Chitin Nanofibrils in Poly(Lactic Acid) (PLA) Nanocomposites: Dispersion and Thermo-Mechanical Properties
Authors: Coltelli Maria-Beatrice , Cinelli Patrizia , Gigante Vito , Aliotta Laura , Morganti Pierfrancesco , Panariello Luca , Lazzeri Andrea
Published: January 2019

Chitin-nanofibrils are obtained in water suspension at low concentration, as nanoparticles normally are, to avoid their aggregation. The addition of the fibrils in molten PLA during extrusion is thus difficult and disadvantageous. In the present paper, the use of poly(ethylene glycol) (PEG) is proposed to prepare a solid pre-composite by water evaporation. The pre-composite is then added to PLA in the extruder to obtain transparent nanocomposites. The amount of PEG and chitin nanofibrils was varied in the nanocomposites to compare the reinforcement due to nanofibrils and plasticization due to the presence of PEG, as well as for extrapolating, where possible, the properties of reinforcement due to chitin nanofibrils exclusively. Thermal and morphological properties of nanocomposites were also investigated. This study concluded that chitin nanofibrils, added as reinforcing filler up to 12% by weight, do not alter the properties of the PLA based material; hence, this additive can be used in bioplastic items mainly exploiting its intrinsic anti-microbial and skin regenerating properties.
Noisy ECG Signal Analysis for Automatic Peak Detection
Authors: D’Aloia Matteo , Longo Annalisa , Rizzi Maria
Published: January 2019

Cardiac signal processing is usually a computationally demanding task as signals are heavily contaminated by noise and other artifacts. In this paper, an effective approach for peak point detection and localization in noisy electrocardiogram (ECG) signals is presented. Six stages characterize the implemented method, which adopts the Hilbert transform and a thresholding technique for the detection of zones inside the ECG signal which could contain a peak. Subsequently, the identified zones are analyzed using the wavelet transform for R point detection and localization. The conceived signal processing technique has been evaluated, adopting ECG signals belonging to MIT-BIH Noise Stress Test Database, which includes specially selected Holter recordings characterized by baseline wander, muscle artifacts and electrode motion artifacts as noise sources. The experimental results show that the proposed method reaches most satisfactory performance, even when challenging ECG signals are adopted. The results obtained are presented, discussed and compared with some other R wave detection algorithms indicated in literature, which adopt the same database as a test bench. In particular, for a signal to noise ratio (SNR) equal to 6 dB, results with minimal interference from noise and artifacts have been obtained, since Se e +P achieve values of 98.13% and 96.91, respectively.
Development of a New Adaptive Backstepping Control Design for a Non-Strict and Under-Actuated System Based on a PSO Tuner
Authors: Humaidi Amjad , Hameed Mustafa
Published: January 2019

In this work, a new adaptive block-backstepping control design algorithm was developed for an under-actuated model (represented by a ball–arc system) to enhance the transient and steady-state behaviors and to improve the robustness characteristics of the controlled system against parameter variation (load change and model uncertainty). For this system, the main mission of the proposed controller is to simultaneously hold the ball at the top of the arc and retain the cart at the required position. The stability of a controlled system based on the proposed adaptive controller was analyzed, and its globally asymptotic stability was proven based on the Lyapunov theorem. A comparative study of adaptive and non-adaptive block-backstepping controllers was conducted in relation to the transient, steady-state, and robustness characteristics. The effectiveness of the controller was verified via simulation within a MATLAB/SIMULINK environment. The simulated results show that the proposed adaptive control strategy could successfully stabilize the under-actuated ball–arc system, regardless of both the regulation problem and the tracking problem. This provides a better dynamic performance and a better load rejection capability, and it performs well in solving the uncertainty problem in the model parameter.
Acknowledgement to Reviewers of Instruments in 2018
Authors:   Editorial Office
Published: January 2019

Rigorous peer-review is the corner-stone of high-quality academic publishing [...]
Circulating MiRNA-195-5p and -451a in Transient and Acute Ischemic Stroke Patients in an Emergency Department
Authors: Giordano Mauro , Ciarambino Tiziana , D’Amico Michele , Trotta Maria , Di Sette Alessandra , Marfella Raffaele , Malatino Lorenzo , Paolisso Giuseppe , Adinolfi Luigi
Published: January 2019

We have evaluated circulating miRNAs (-195-5p and -451a) in subjects with acute ischemic stroke (AIS) and in patients with transient ischemic attack (TIA). In this study, 18 subjects with AIS and 18 patients with TIA were enrolled and examined at admission (T0) and at 24 h and 48 h after admission, and compared to 20 controls (C). At T0, circulating miRNA-195-5p and -451a were significantly upregulated in both AIS and TIA patients, compared to C. We also observed a progressive reduction of circulating miRNA levels at 24 h and 48 h in both AIS and TIA patients. Hypoxia inducible factor 1alpha (HIF-1α) serum level was significantly increased at T0, in both AIS and TIA patients, in comparison to C (both p < 0.01 vs. C) and it decreased in both AIS and TIA patients at 24 h and at 48 h, in comparison to T0 (both p < 0.01 vs. T0). Vascular endothelial growth factor (VEGF) serum level was significantly decreased at T0, in both AIS and TIA patients, if compared to C (both p < 0.01 vs. C) and increased, in both AIS and TIA patients, at 24 h and 48 h, if compared to T0 (both p < 0.01 vs. T0). The elevated expression of miRNA-195-5p and miRNA-451a significantly decreased over time at 24 h and 48 h, and it is associated with decreased HIF-α levels and increased VEGF serum levels. These data may suggest a role for this miRNAs as biomarker in the pathogenesis and prognosis of AIS patients and for the first time also in TIA patients.
Women’s Preferences for Maternal Healthcare Services in Bangladesh: Evidence from a Discrete Choice Experiment
Authors: Mahumud Rashidul Alam , Alamgir Nadia Ishrat , Hossain Md. Tarek , Baruwa Elaine , Sultana Marufa , Gow Jeff , Alam Khorshed , Ahmed Syed Masud , Khan Jahangir A.M.
Published: January 2019

Despite substantial improvements in several maternal health indicators, childbearing and birthing remain a dangerous experience for many women in Bangladesh. This study assessed the relative importance of maternal healthcare service characteristics to Bangladeshi women when choosing a health facility to deliver their babies. The study used a mixed-methods approach. Qualitative methods (expert interviews, focus group discussions) were initially employed to identify and develop the characteristics which most influence a women’s decision making when selecting a maternal health service facility. A discrete choice experiment (DCE) was then constructed to elicit women’s preferences. Women were shown choice scenarios representing hypothetical health facilities with nine attributes outlined. The women were then asked to rank the attributes they considered most important in the delivery of their future babies. A Hierarchical Bayes method was used to measure mean utility parameters. A total of 601 women completed the DCE survey. The model demonstrated significant predictive strength for actual facility choice for maternal health services. The most important attributes were the following: consistent access to a female doctor, the availability of branded drugs, respectful provider attitudes, a continuum of maternal healthcare including the availability of a C-section delivery and lesser waiting times. Attended maternal healthcare utilisation rates are low despite the access to primary healthcare facilities. Further implementation of quality improvements in maternal healthcare facilities should be prioritised.
Finance and Jobs: How Financial Markets and Prudential Regulation Shape Unemployment Dynamics
Authors: Ernst Ekkehard
Published: January 2019

This article explores the impact of financial market regulation on jobs. It argues that understanding the impact of finance on labor markets is key to an understanding of the trade-off between economic stability and financial sector growth. The article combines information on labor market flows with indicators of financial market development and reforms to assess the implications of financial markets on employment dynamics directly, using information from the International Labour Organization (ILO) datatabse on unemployment flows. On the basis of a matching model of the labor market, it analyses the economic, institutional, and policy determinants of unemployment in- and out-flows. Against a set of basic controls, we present evidence regarding the relationship between financial sector development and reforms and their impact on unemployment dynamics. Using scenario analysis, the article demonstrates the importance of broad financial sector re-regulation to stabilize unemployment inflows and to promote faster employment growth. In particular, we find that encompassing financial sector regulation, had it been in place prior to the global financial crisis in 2008, would have helped a faster recovery in jobs.
Origin of Life’s Building Blocks in Carbon- and Nitrogen-Rich Surface Hydrothermal Vents
Authors: Rimmer Paul B. , Shorttle Oliver
Published: January 2019

There are two dominant and contrasting classes of origin of life scenarios: those predicting that life emerged in submarine hydrothermal systems, where chemical disequilibrium can provide an energy source for nascent life; and those predicting that life emerged within subaerial environments, where UV catalysis of reactions may occur to form the building blocks of life. Here, we describe a prebiotically plausible environment that draws on the strengths of both scenarios: surface hydrothermal vents. We show how key feedstock molecules for prebiotic chemistry can be produced in abundance in shallow and surficial hydrothermal systems. We calculate the chemistry of volcanic gases feeding these vents over a range of pressures and basalt C/N/O contents. If ultra-reducing carbon-rich nitrogen-rich gases interact with subsurface water at a volcanic vent they result in 10 − 3 – 1 M concentrations of diacetylene (C4H2), acetylene (C2H2), cyanoacetylene (HC3N), hydrogen cyanide (HCN), bisulfite (likely in the form of salts containing HSO3−), hydrogen sulfide (HS−) and soluble iron in vent water. One key feedstock molecule, cyanamide (CH2N2), is not formed in significant quantities within this scenario, suggesting that it may need to be delivered exogenously, or formed from hydrogen cyanide either via organometallic compounds, or by some as yet-unknown chemical synthesis. Given the likely ubiquity of surface hydrothermal vents on young, hot, terrestrial planets, these results identify a prebiotically plausible local geochemical environment, which is also amenable to future lab-based simulation.
Investigations of the Hydrogen Bonds and Vibrational Spectra of Clathrate Ice XVI
Authors: Wang Ze-Ren , Zhu Xu-Liang , Jiang Lu , Zhang Kai , Luo Hui-Wen , Gu Yue , Zhang Peng
Published: January 2019

Natural gas hydrates are ice-like crystalline materials formed from natural gas and clathrate ice under high pressure and low temperature. Ice XVI, the first S-II type clathrate ice produced in the lab, was simulated by first-principles density functional theory with the CASTEP code. A 34-molecule supercell was built to mimic the hydrogen-disordered structure. The vibrational spectra were calculated as a reference for inelastic neutron scattering (INS), infrared (IR) absorption, and Raman scattering experiments. Two kinds of H-bond vibration modes corresponding to two different bond strengths were found in our previous studies. In this paper, the statistics of distribution calculated by integrating these two kinds of modes was found to match the phonon density of states (PDOS) very well. We confirmed that the two basic types of H-bonds also appeared in clathrate ice XVI. The typical normal modes were analyzed to illustrate the dynamic process of lattice vibrations.
From Design to Manufacture of a Carbon Fiber Monocoque for a Three-Wheeler Vehicle Prototype
Authors: Messana Alessandro , Sisca Lorenzo , Ferraris Alessandro , Airale Andrea Giancarlo , de Carvalho Pinheiro Henrique , Sanfilippo Pietro , Carello Massimiliana
Published: January 2019

This paper describes the design process of the monocoque for IDRAkronos, a three-wheeler hydrogen prototype focused on fuel efficiency, made to compete at the Shell Eco-Marathon event. The vehicle takes advantage of the lightweight and high mechanical performance of carbon fiber to achieve minimal mass and optimized fuel consumption. Based on previous experiences and background knowledge, the authors describe their work toward a design that integrates aerodynamic performance, style, structural resistance and stiffness. A portrayal of the objectives, load cases, simulations and production process—that lead to a final vehicle winner of the Design Award and 1st place general at the 2016 competition—is presented and discussed.
Preparation and Properties of Acetoacetic Ester-Terminated Polyether Pre-Synthesis Modified Phenolic Foam
Authors: Ge Tiejun , Tang Kaihong , Tang Xiaojun
Published: January 2019

In the present study, acetoacetic ester-terminated polyether was selected as a modifier to prepare a new type of polyether phenolic resin, which was successfully prepared by pre-synthesis modification. It is used to prepare interpenetrating cross-linked network structure modified phenolic foam with excellent mechanical properties. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1H NMR, 13C NMR) were used to characterize the molecular structure of the polyether phenolic resin. The results showed that the acetoacetic ester-terminated polyether successfully modified the phenolic resin and introduced a polyether skeleton into the resin structure. The effect of changing the added amount of acetoacetic ester-terminated polyether from 10% to 20% of the phenol content on the mechanical properties and microstructure of the modified phenolic foam was investigated. The results showed that when the amount of acetoacetic ester-terminated polyether was 16% the amount of phenol, this resulted in the best toughness of the modified foam, which had a bending deflection that could be increased to more than three times that of the base phenolic foam. The modified phenolic foam cell diameter was reduced by 36.3%, and the distribution was more uniform, which formed a denser network structure than that of the base phenolic foam. The bending strength was increased by 0.85 MPa, and the pulverization rate was as low as 1.3%.
The Effect of Swinging Ball Heads with Different Arrangements in Multi-Point Stretch-Forming Process
Authors: Xing Jian , Cheng Yan-yan , Yi Zhuo
Published: January 2019

To improve the effect of multi-point stretch forming of sheet metal, it is proposed in this paper to replace a fixed ball head with a swinging ball head. According to the multi-point dies with different arrangements, this research establishes finite element models of the following stretch forming, i.e., fixed ball heads with conventional arrangement, swinging ball heads with conventional arrangement, swinging ball heads with declining staggered arrangement, and swinging ball heads with parallel staggered arrangement, and then numerical simulation is performed. The simulation results show that by replacing a fixed ball head with a swinging ball head, the surface indentation of the part formed was effectively suppressed, the stress and tension strain distribution of the part formed was improved, and the forming quality was improved; the thickness of the elastic pad was reduced, the springback was reduced and the forming accuracy was improved; and when the ball head was applied to a multi-point die with staggered arrangement, a better forming result was achieved, where the best forming result was achieved in combining the swinging ball heads with the multi-point die with a parallel staggered arrangement. Forming experiments were carried out, and the experimental results were consistent with the trend of numerical simulation results, which verified the correctness of the numerical simulation.
Experimental and Numerical Study on Shear Resistance of Notched Perfobond Shear Connector
Authors: Zheng Shuangjie , Liu Yuqing , Liu Yangqing , Zhao Chen
Published: January 2019

In steel and concrete composite bridges, it is difficult to perforate the reinforcing bars through the circular holes of conventional perfobond shear connectors with multi-ribs. To ease the installation of perforating rebars, an alternative notched perfobond shear connector was proposed by cutting out the edge of the circular hole. This paper presents the push-out test results of six specimens which were fabricated and loaded to failure. The main purpose was to compare the failure mode, shear capacity and slip behavior of perfobond shear connectors using circular holes and notched holes. Furthermore, 43 nonlinear finite element simulations were performed to further study the effects of several variables, including the hole diameter, the hole distance, the hole number, the cut width, the perfobond thickness, the concrete strength, the rebar diameter, the rebar strength, and the steel strength. The parametric results were generated to evaluate the shear capacity equations for perfobond shear connectors. Finally, an analytical model was developed to estimate the shear capacity of notched perfobond shear connectors.
The Influence of Oxygen Concentration during MAX Phases (Ti3AlC2) Preparation on the α-Al2O3 Microparticles Content and Specific Surface Area of Multilayered MXenes (Ti3C2Tx)
Authors: Scheibe Błażej , Kupka Vojtech , Peplińska Barbara , Jarek Marcin , Tadyszak Krzysztof
Published: January 2019

The high specific surface area of multilayered two-dimensional carbides called MXenes, is a critical feature for their use in energy storage systems, especially supercapacitors. Therefore, the possibility of controlling this parameter is highly desired. This work presents the results of the influence of oxygen concentration during Ti3AlC2 ternary carbide—MAX phase preparation on α-Al2O3 particles content, and thus the porosity and specific surface area of the Ti3C2Tx MXenes. In this research, three different Ti3AlC2 samples were prepared, based on TiC-Ti2AlC powder mixtures, which were conditioned and cold pressed in argon, air and oxygen filled glove-boxes. As-prepared pellets were sintered, ground, sieved and etched using hydrofluoric acid. The MAX phase and MXene samples were analyzed using scanning electron microscopy and X-ray diffraction. The influence of the oxygen concentration on the MXene structures was confirmed by Brunauer-Emmett-Teller surface area determination. It was found that oxygen concentration plays an important role in the formation of α-Al2O3 inclusions between MAX phase layers. The mortar grinding of the MAX phase powder and subsequent MXene fabrication process released the α-Al2O3 impurities, which led to the formation of the porous MXene structures. However, some non-porous α-Al2O3 particles remained inside the MXene structures. Those particles were found ingrown and irremovable, and thus decreased the MXene specific surface area.
Improved Self-Cleaning Properties of Photocatalytic Gypsum Plaster Enriched with Glass Fiber
Authors: Zając Kamila , Janus Magdalena , Morawski Antoni W.
Published: January 2019

In the study the self-cleaning properties of photoactive gypsum plasters are presented. The modified gypsum plasters were obtained by addition of 1 and 3 wt.% of nitrogen-modified titanium dioxide (TiO2/N) and 0.1, 0.3, and 0.5 wt.% of glass fiber. The self-cleaning ability of the obtained materials was tested during two dyes decomposition: Methylene Blue (MB) and Reactive Orange (RO). It was found that presence of glass fiber increased photocatalytic activity of modified gypsum plasters, which may be due to the fact glass fiber may act as ducts for light and transport it to sites screened by TiO2 or glass fiber can retard charge recombination. Moreover, unexpectedly the addition of glass fiber did not increase the mechanical properties of modified gypsum plasters, which may be because gypsum does not strongly adhere to the surface of glass fibers.
Correlation of Different Electrical Parameters of Solar Cells with Silver Front Electrodes
Authors: Musztyfaga-Staszuk Małgorzata , Janicki Damian , Panek Piotr
Published: January 2019

This work presents comparison results of the selected electrical parameters of silicon solar cells manufactured with silver front electrodes which were co-fired in an infrared belt furnace in the temperature range of 840–960 °C. The commercial paste (PV19B) was used for the metallization process. Electrical properties of a batch of solar cells fabricated in one cycle were investigated. Three methods were used, including measurement of the current-voltage characteristics (I-V), measurement of contacts’ resistivity using the transmission Line model method (TLM), and measurement of contacts’ resistivity using the potential difference method (PD). This work is focused on both the different metallization temperatures of co-firing of solar cells and measurements using the above-mentioned methods. It is shown that the solar cell parameters measured with three methods have different, but strongly correlated values. Moreover, the comparative analysis was performed of the investigations of the same photovoltaic solar cells using both the TLM method and independent research stands (including one non-commercial and two commercial ones) at three different scientific units. In the PD and TLM methods, the same calculation formulae are used. It can be stated, comparing methods I-V, PD, and TLM, that for each, different parameters are determined to assess the electrical properties of the solar cell.
Microstructure and Mechanical Properties of an Ultrasonic Spot-Welded Aluminum-to-Aluminum Joint: Response to Interlayer Thickness
Authors: Ni Zeng-Lei , Ye Fu-Xing
Published: January 2019

To enhance the mechanical strength of an ultrasonic spot-welded Al/Al joint, an Al 2219 particle interlayer was placed between the two Al sheets during the ultrasonic spot welding process. The effects of the interlayer thickness on the microstructure and mechanical performances of the joints were systematically investigated. The results showed that, the optimum thickness of the Al 2219 particle interlayer was 10 μm, which was beneficial to enhance the weld interface temperature up to 402 °C. The bonding interface of Al/Al 2219 with a wave-like shape was sound, and no significant diffusion layer occurred. The peak lap shear tensile strength (~84.8 MPa) was obtained, which was 36% higher than that (~67.3 MPa) for the joint without the Al 2219 particle interlayer. The strengthening mechanism is caused by the increase of plastic deformation and contact areas in the weld interface.
Characterization of the Specific Mode of Action of a Chitin Deacetylase and Separation of the Partially Acetylated Chitosan Oligosaccharides
Authors: Zhu Xian-Yu , Zhao Yong , Zhang Huai-Dong , Wang Wen-Xia , Cong Hai-Hua , Yin Heng
Published: January 2019

Partially acetylated chitosan oligosaccharides (COS), which consists of N-acetylglucosamine (GlcNAc) and glucosamine (GlcN) residues, is a structurally complex biopolymer with a variety of biological activities. Therefore, it is challenging to elucidate acetylation patterns and the molecular structure-function relationship of COS. Herein, the detailed deacetylation pattern of chitin deacetylase from Saccharomyces cerevisiae, ScCDA2, was studied. Which solves the randomization of acetylation patterns during COS produced by chemical. ScCDA2 also exhibits about 8% and 20% deacetylation activity on crystalline chitin and colloid chitin, respectively. Besides, a method for separating and detecting partially acetylated chitosan oligosaccharides by high performance liquid chromatography and electrospray ionization mass spectrometry (HPLC-ESI-MS) system has been developed, which is fast and convenient, and can be monitored online. Mass spectrometry sequencing revealed that ScCDA2 produced COS with specific acetylation patterns of DAAA, ADAA, AADA, DDAA, DADA, ADDA and DDDA, respectively. ScCDA2 does not deacetylate the GlcNAc unit that is closest to the reducing end of the oligomer furthermore ScCDA2 has a multiple-attack deacetylation mechanism on chitin oligosaccharides. This specific mode of action significantly enriches the existing limited library of chitin deacetylase deacetylation patterns. This fully defined COS may be used in the study of COS structure and function.
Exploration of Indole Alkaloids from Marine Fungus Pseudallescheria boydii F44-1 Using an Amino Acid-Directed Strategy
Authors: Yuan Mei-Xiang , Qiu Yi , Ran Yan-Qin , Feng Gong-Kan , Deng Rong , Zhu Xiao-Feng , Lan Wen-Jian , Li Hou-Jin
Published: January 2019

The composition of the culture medium has great influence on the metabolite production of the marine fungus Pseudallescheria boydii F44-1. By adding amino acids to GPY culture medium, two new bisindole alkaloids, pseudboindoles A and B (1 and 2), together with 11 known indole alkaloids were isolated from the culture broth. Their structures were elucidated by comprehensive analysis of the NMR, MS, IR, and UV spectra. The 3,3′-cyclohexylidenebis(1H-indole) (3) showed cytotoxic activity against various cancer cell lines.
Testing the Neuroprotective Properties of PCSO-524® Using a Neuronal Cell Cycle Suppression Assay
Authors: Zhu Beika , Zhang Yang , Herrup Karl
Published: January 2019

Cell cycle reentry is a unified mechanism shared by several neurodegenerative diseases, including Alzheimer’s disease (AD) and Ataxia Telangiectasia (A-T). This phenotype is often related to neuroinflammation in the central nervous system. To mimic brain inflammation in vitro, we adopted the previously established method of using conditioned medium collected from activated THP-1 cells and applied it to both differentiated HT22 cells and primary neurons. Unscheduled cell cycle events were observed in both systems, indicating the potential of this approach as an in vitro model of neurodegenerative disease. We used this assay to measure the neuroprotective effects of New Zealand green-lipped mussel extract, PCSO-524®, to protect post-mitotic cells from cell cycle reentry. We found that, both in vitro and in an animal model, PCSO-524® displayed promising neuroprotective effects, and thus has potential to postpone or prevent the onset of neurodegenerative disease.
From “Black Box” to a Real Description of Overall Mass Transport through Membrane and Boundary Layers
Authors: Nagy Endre , Vitai Márta
Published: January 2019

The “black box” model defines the enhancement, E the polarization modulus, C ∗ / C o and the intrinsic enhancement, E o without knowing the transport mechanism in the membrane. This study expresses the above-mentioned characteristic parameters, simultaneously taking into account the mass transport expressions developed for both the polarization and the membrane layers. Two membrane models are studied here, namely a solution-diffusion model characterizing solute transport through a dense membrane and a solution-diffusion plus convection model characterizing transport through a porous membrane due to transmembrane pressure difference. It is shown that the characteristic parameters of the “black box” model (E, E o or C ∗ / C o ) can be expressed as a function of the transport parameters and independently from each other using two-layer models. Thus, membrane performance could be predicted by means of the transport parameters. Several figures show how enhancement and the polarization modulus varied as a function of the membrane Peclet number and the solubility coefficient. Enhancement strongly increased up to its maximum value when H > 1, in the case of transport through a porous membrane, whereas its change remained before unity in the case of a dense membrane. When the value of H < 1, the value of E gradually decreased with increasing values of the membrane Peclet number.
Perfluoropolymer/Molecular Sieve Mixed-Matrix Membranes
Authors: Golemme Gianni , Santaniello Anna
Published: January 2019

Despite the outstanding chemical, thermal and transport properties of amorphous and glassy perfluorinated polymers, only few works exist on the preparation and transport properties of perfluoropolymer/molecular sieves mixed-matrix membranes (MMMs), probably because of their poor compatibility. In this review, the compatibilization of ceramic molecular sieves with perfluorinated matrices is considered first, examining the effect of the surface treatment on the gas transport properties of the filler. Then the preparation of the defect-free hybrid membranes and their gas separation capabilities are described. Finally, recent modelling of the gas transport properties of the perfluoropolymer MMMs is reviewed. The systematic use of molecular sieves of different size and shape, either permeable or impermeable, and the calculation of the bulk transport properties of the molecular sieves—i.e., the unrestricted diffusion and permeability—allow to understand the nature of the physical phenomena at work in the MMMs, that is the larger the perfluoropolymer fractional free volume at the interface, and restricted diffusion at the molecular sieves. This knowledge led to the formulation of a new four-phase approach for the modelling of gas transport. The four-phase approach was implemented in the frame of the Maxwell model and also for the finite element simulation. The four-phase approach is a convenient representation of the transport in MMMs when more than one single interfacial effect is present.
Preparation of Layer-by-Layer Nanofiltration Membranes by Dynamic Deposition and Crosslinking
Authors: Liu Yan , Chen George Q. , Yang Xiuli , Deng Huining
Published: January 2019

In recent decades, the advancements in layer-by-layer (LBL) assembly technology have provoked increasing interest in the preparation of multilayer polyelectrolyte membranes with excellent performance. In the current study, a novel nanofiltration (NF) membrane was prepared by pressure-driven layer-by-layer (LBL) assembly of polyethylenimine (PEI) and polyacrylicacid (PAA) on a porous substrate with chemical crosslinking. The effect of deposition pressure on separation performance of the prepared membranes was studied. The surface morphology, hydrophilicity and the charge property of the dynamically-deposited membranes were compared with those prepared by static adsorption. The characterization results showed that dynamic deposition process resulted in a smoother membrane surface with improved hydrophilicity. The mechanism of water-path formation was proposed to interpret the effect of pressure on the membrane performance. Glutaraldehyde (GA) was used as a crosslinker to reduce the number of polyelectrolyte bilayers for obtaining good separation performance. The rejections of different inorganic salts of the dynamically-deposited NF membrane were also investigated.
The Effect of Mo and Dispersoids on Microstructure, Sintering Behavior, and Mechanical Properties of W-Mo-Ni-Fe-Co Heavy Tungsten Alloys
Authors: Chen Chun-Liang , Sutrisna
Published: January 2019

W-Mo-Ni-Fe-Co heavy tungsten alloys were fabricated by mechanical alloying. The effects of Mo and oxide dipsersoids on the characteristics and properties of the model alloys were investigated. In this study, the W-Mo matrix and γ-Ni(Fe,Co) binder phase were further synthesized with Y2O3 by a secondary ball milling method. The results suggest that the microstructure and sintering behavior of the model alloys are strongly influenced by the dispersed oxide particles. The model alloys with the Y2O3 addition demonstrate grain refinement and uniform microstructure. The dispersed particles could act as an inhibitor for diffusion of tungsten atoms and grain growth, promoting the formation of solid state during sintering. Consequently, good densification, high hardness, and elastic modulus of alloys can be achieved.
Material Characterization, Thermal Analysis, and Mechanical Performance of a Laser-Polished Ti Alloy Prepared by Selective Laser Melting
Authors: Li Yu-Hang , Wang Bing , Ma Cheng-Peng , Fang Zhi-Hao , Chen Long-Fei , Guan Ying-Chun , Yang Shou-Feng
Published: January 2019

The laser polishing technique offers an adaptable, accurate, and environmentally friendly solution to enhance the surface quality of additive manufactured metallic components. Recent work has shown that the surface roughness of laser additive manufactured metallic alloys can be significantly reduced via the laser polishing method. This paper examines the mechanical performances of a laser polished surface fabricated by selective laser melting (SLM). Compared with the original SLM surface, systematic measurements revealed that the surface roughness of the laser polished surface can be effectively reduced from 6.53 μm to 0.32 μm, while the microhardness and wear resistance increased by 25% and 39%, respectively. Through a thermal history analysis of the laser polishing process using the finite element model, new martensitic phase formation in the laser polished layer is carefully explained, which reveals significant effects on residual stress, strength, and fatigue. These findings establish foundational data to predict the mechanical performance of laser polished metallic components fabricated by additive manufacturing methods, and pave the way for functional surface design with practical application via the laser process.
High Strain Rate Behavior of Ultrafine Grained AA2519 Processed via Multi Axial Cryogenic Forging
Authors: Azimi Amin , Owolabi Gbadebo Moses , Fallahdoost Hamid , Kumar Nikhil , Warner Grant
Published: January 2019

The present work deals with studies on the dynamic behavior of ultrafine grained AA2519 alloy synthesized via cryogenic forging (CF) and room temperature forging (RTF) techniques. A split-Hopkinson pressure bar was used to perform high strain rate tests on the processed samples and the microstructures of the samples were characterized before and after impact tests. Electron backscatter diffraction (EBSD) maps demonstrated a significant grain size refinement from ~740 nm to ~250 nm as a result of cryogenic plastic deformation showing higher dislocation densities and stored strains in the CF sample when compared to the RTF sample. This microstructure modification caused the increase of dynamic flow stress in this alloy. In addition, the aluminum matrix of the CF alloy is more densely populated with fragmented particles than the RTF alloy due to the heavier plastic deformation applied to the cryogenically forged alloy. The results obtained from the stress–strain curve for the RTF sample showed intense thermomechanical instabilities in the RTF sample which led to a severe thermal softening and the subsequent sharp drop in the flow stress. However, no significant decrease was observed in the stress–strain curve of the CF alloys with ultrafine grains which means that thermal softening would probably not be the most effective failure mechanism. Furthermore, higher level of sensitivity of CF alloys to strain rates was observed which is ascribed to transition of rate-controlling plastic deformation mechanisms. In the post-mortem microstructure investigation, deformed and transformed adiabatic shear bands (ASBs) were identified on the RTF alloy when the strain rate is over 4000 s−1 at which it had experienced a significant thermal softening. On the other hand, circular path and aligned split arcs are the various shapes of the deformed ASB seen at no earlier than 4500 s−1 in the CF alloys. This is associated with the crack failure caused by grain boundary sliding.
Phosphorus Equilibrium Between Liquid Iron and CaO-SiO2-MgO-Al2O3-FeO-P2O5 Slags: EAF Slags, the Effect of Alumina and New Correlation
Authors: N. Assis Andre , A. Tayeb Mohammed , Sridhar Seetharaman , J. Fruehan Richard
Published: January 2019

The increased use of electric arc furnace (EAF) steelmaking using up to 100% direct reduced iron (DRI) has prompted an interest in better control of phosphorus since iron ore and, consequently, DRI have higher phosphorus and silica compared to scrap. There is limited work reported on slag chemistries corresponding to that in the EAF when DRI is used. In the current research, phosphorus equilibria between molten Fe–P alloys and CaO-SiO2-Al2O3-P2O5-FeO-MgOsaturated slags were investigated. The results indicate that there is a significant decrease in the phosphorus partition coefficient (LP) as alumina in the slag increases. The observed effect of alumina on the phosphorus partition is probably caused by the decrease in the activities of iron oxide and calcium oxide. Finally, an equilibrium correlation for phosphorus partition as a function of slag composition and temperature has been developed. It includes the effect of alumina and silica and is suitable for both oxygen and electric steelmaking-type slags.
The Application of DIC Technique to Evaluate Residual Tensile Strength of Aluminum Alloy Plates with Multi-Site Damage of Collinear and Non-Collinear Cracks
Authors: Chen Yajun , Ji Chunming , Zhang Changtian , Sun Shengjie
Published: January 2019

This paper introduces an aviation industrial application of digital image correlation (DIC) technique on the measurement of residual tensile strength (RTS). In order to investigate multi-site damage (MSD) that is common in the fuselage of aging aircraft, RTS of 2024-T4 aluminum alloy sheet with MSD was evaluated using DIC technique. Firstly, the four-factor and three-level orthogonal experiment was designed to optimize the DIC method to control the strain calculation error by considering subset size, interpolation tap, calibration score and step size. Secondly, RTS and strain fields were generated to analyze the path of crack propagation. The results show the optimal factor combination is 0.018 of calibration score, 23 pixels of subset size, step size is 1/4 of subset size and the filter size of interpolation calibration is 8 pixels. With the increase of spacing between adjacent holes, the RTS increases and the collinear cracked specimen becomes more perilous than that of non-collinear cracked while the hole spacing is 25 mm from the statistical analysis. Based on the Net section yield criterion, the RTS was calculated, which can give a conservative prediction of RTS.
Study of Sputtered ITO Films on Flexible Invar Metal Foils for Curved Perovskite Solar Cells
Authors: Seok Hae-Jun , Kim Han-Ki
Published: January 2019

We have studied characteristics of tin-doped indium oxide (ITO) films sputtered on flexible invar metal foil covered with an insulating SiO2 layer at room temperature to use as transparent electrodes coated substrates for curved perovskite solar cells. Sheet resistance, optical transmittance, surface morphology, and microstructure of the ITO films on SiO2/invar substrate are investigated as a function of the thickness from 50 to 200 nm. The optimized ITO film exhibits a low sheet resistance of 50.21 Ohm/square and high optical transmittance of up to 94.31% even though it is prepared at room temperature. In particular, high reflectance of invar metal substrate could enhance the power conversion efficiency of curved perovskite solar cell fabricated on the ITO/SiO2/invar substrate. In addition, critical bending radius of the 150 nm-thick ITO film is determined by lab-designed outer and inner bending tests to show feasibility as flexible electrode. Furthermore, dynamic fatigue test is carried out to show flexibility of the ITO film on invar metal substrate. This suggests that the ITO/SiO2/invar substrate can be applied as flexible electrodes and substrates for curved perovskite solar cells.
Aluminum Foam-Filled Steel Tube Fabricated from Aluminum Burrs of Die-Castings by Friction Stir Back Extrusion
Authors: Hangai Yoshihiko , Kobayashi Ryusei , Suzuki Ryosuke , Matsubara Masaaki , Yoshikawa Nobuhiro
Published: January 2019

A mixture of Al burrs of Al high-pressure die-castings and a blowing agent powder was used to fabricate Al foam-filled steel tubes by friction stir back extrusion (FSBE). It was shown that the mixture can be sufficiently consolidated to form an Al precursor that is coated on the inner surface of a steel tube by the plastic flow generated during FSBE. Namely, a precursor coated steel tube can be fabricated from Al burrs by FSBE. By heat treatment of the precursor coated steel tube, an Al foam-filled steel tube can be fabricated. Al foam was sufficiently filled in the steel tube, and the porosity was almost homogeneously distributed in the entire sample. In compression tests of the samples, the Al foam-filled steel tube fabricated from Al burrs exhibited similar compression properties to an Al foam-filled steel tube fabricated from the bulk Al precursor. Consequently, it was shown that an Al foam-filled steel tube cost-effectively fabricated from Al burrs by FSBE compares favorably with an Al foam-filled steel tube fabricated from the bulk Al precursor.
Metal Posts and the Effect of Material–Shape Combination on the Mechanical Behavior of Endodontically Treated Anterior Teeth
Authors: Gloria Antonio , Maietta Saverio , Richetta Maria , Ausiello Pietro , Martorelli Massimo
Published: January 2019

The control of the process–structure–property relationship of a material plays an important role in the design of biomedical metal devices featuring desired properties. In the field of endodontics, several post-core systems have been considered, which include a wide range of industrially developed posts. Endodontists generally use posts characterized by different materials, sizes, and shapes. Computer-aided design (CAD) and finite element (FE) analysis were taken into account to provide further insight into the effect of the material–shape combination of metal posts on the mechanical behavior of endodontically treated anterior teeth. In particular, theoretical designs of metal posts with two different shapes (conical-tapered and conical-cylindrical) and consisting of materials with Young’s moduli of 110 GPa and 200 GPa were proposed. A load of 100 N was applied on the palatal surface of the crown at 45° to the longitudinal axis of the tooth. Linear static analyses were performed with a non-failure condition. The results suggested the possibility to tailor the stress distribution along the metal posts and at the interface between the post and the surrounding structures, benefiting from an appropriate combination of a CAD-based approach and material selection. The obtained results could help to design metal posts that minimize stress concentrations.