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1 Temperature-independent piezoresistive sensors based on carbon nanotube/polymer nanocomposite 2018-05-21             

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Publication date: October 2018
Source:Carbon, Volume 137

Author(s): Shen Gong, Di Wu, Yixuan Li, Mengyin Jin, Tao Xiao, Yang Wang, Zhu Xiao, Zhenghong Zhu, Zhou Li

Temperature-independent property and high piezoresistivity are critical for carbon nanotube polymer nanocomposites with sensing capability. In this work, a temperature-independent CNT/Epoxy resin nanocomposite was fabricated successfully. This composite has good and stable piezoresistivity between 233 K and 373 K. By developing a multi-scale percolation network model, this work also reveals theoretically the inherent mechanisms to obtain temperature-independent sensors. In order to fully consider the tube–tube and/or tube–matrix interaction in the composite, the structural distortion of nanotubes is determined self-consistently by minimizing the pseudo-potential energy and the thermally assisted tunneling transport is calculated by the Landauer-Büttiker formula. Simulation results show that temperature-independent composite with further improved piezoresistivity (gauge factor > 40) can be achieved by dispersing the treated and selected CNTs to the theoretically matched polymer matrix. These temperature-independent, highly sensitive, low cost and homogeneous sensors have a great potential for wide range applications, such as in electronic skin, man-machine interaction and body monitoring.

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2 Sparse classification based on dictionary learning for planet bearing fault identification 2018-05-21             

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Publication date: 15 October 2018
Source:Expert Systems with Applications, Volume 108

Author(s): Chuan Zhao, Zhipeng Feng, Xiukun Wei, Yong Qin

Planet bearing vibrations feature high complexity due to the intricate kinematics and multiple modulation effects. This leads to difficulty in planet bearing fault identification. In order to overcome this difficulty, a sparse classification framework based on dictionary learning is proposed. It operates directly on raw signals and is free from steps involved in conventional pattern identification such as feature design which requires prior expertise. First, a raw signal matrix is generated by partitioning the raw signal into segments, where each segment in all signal states has the same number of data points, and the length of the segment should guarantee that at least two adjacent fault impulses with the maximum interval can occur. Then, a dictionary initialized with the training sample set is learnt from the signal matrix, based on which the sparse representation is carried out afterwards. A dictionary learnt over signals under a certain state is best suited for signal reconstruction under the same state only but cannot recover signals well under other states. Inspired by this fact, sparse classification can be accomplished by comparing signal recovery errors over dictionaries under different states. The proposed method is validated using the experimental data of a planetary gearbox. Localized faults on the outer race, roller element and inner race of planet bearings are all identified successfully.





3 Linear approximation of underwater sound speed profile: Precision analysis in direct and inverse problems 2018-05-21             

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Publication date: November 2018
Source:Applied Acoustics, Volume 140

Author(s): Xun Wang, Shahram Khazaie, Xue Chen

Sound speed is one of the key sources of uncertainty in an underwater environment. The wave equation for a complex sound speed profile (SSP) cannot be analytically solved and numerical solutions generally involve high computational costs. A relatively simple way is to approximate the SSP by assuming it as horizontally stratified, vertically multi-layered and linearly varied with respect to water depth in each layer. This approximative model leads to a fast computation of the sound propagation. However, the error of SSP results in an inaccurate sound field computation, thus the model accuracy in terms of error propagation in both direct and inverse problems should be investigated. Rapidly developing numerical techniques are currently able to accurately simulate the sound propagation in a complex configuration, such that the difference between a real case with a complex SSP and its approximation can be precisely quantified. In this paper, the sound propagation with a complex SSP is simulated via a full wave numerical approach, known as the spectral element method. The efficiency of SSP linear approximation with various layer number (corresponding to different sound speed error) is quantified via transmission loss forecast (direct problem) and sound source localization error (inverse problem), respectively. The precision analysis is able to guide the choice of optimal approximate model for different scenarios, which is a trade-off between the computational cost and the model accuracy.





4 Zn2+ detection by MRI using Ln3+-based complexes: The central role of coordination chemistry 2018-05-20             

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Publication date: 15 August 2018
Source:Coordination Chemistry Reviews, Volume 369

Author(s): Célia S. Bonnet

This review deals with the rational design of Gd3+-based complexes for Zn2+ detection. It describes the different possible mechanisms underlying Zn2+ detection with such responsive probes. Those probes are composed of three parts: the Gd3+ complex, the Zn2+ binding unit, and a linker. The role and the importance of each part will be described separately through various examples, and it will be shown how it affects the stability, affinity, and efficacy of the probes. Finally, it will be demonstrated how, knowing the mechanism of action of the complex for Zn2+ detection, such probes can be optimized. The aim is to try to establish relationships between the structure and the efficacy of the agents to design rationally more efficient contrast agents in the future.

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5 Simultaneous inhibition of acrylamide and oil uptake in deep fat fried potato strips using gum Arabic-based coating incorporated with antioxidants extracted from spices 2018-05-19             

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Publication date: October 2018
Source:Food Hydrocolloids, Volume 83

Author(s): Rasha Mousa Ahmed Mousa

Modified hydrocolloid gum Arabic (GA) layers on potato strips have been easily prepared by incorporating individual, binary or ternary combinations of antioxidants extracted from widely used spices (black pepper, red chili, turmeric, coriander and cumin) with gum Arabic before deep-frying. The methodological approach for antioxidants incorporation with GA has been firstly investigated to reduce simultaneously acrylamide (AA) and oil uptake in the final deep fat fried potato strips (DFFPS). Results revealed that the antioxidant capacity of markers and their adsorbed amounts are limiting factors for the efficiency of modified GA layer. It is interesting to observe that the use of antioxidants in ternary combinations improved markedly the performance of GA for the inhibition of AA giving values in the range of 112.1 ± 4.5 to 560.4 ± 6.6 μg/kg that are very close or lower than the acceptable EU benchmark level 500 μg/kg AA in DFFPS. The addition of ternary mixtures (1.5%, w/v) of red chili, turmeric and coriander into the GA (1%, w/v) coating solution (1:2, w/v) for 60 min at ambient temperature has been identified as the most promising inhibitor of AA formation (reduction up to 88%) and oil uptake (reduction up to 84.1%). However, non-modified GA layer attenuated only 20% of AA formation (747.2 ± 9.0 μg/kg) and 45.8% of oil uptake compared with the control sample. These results could be attributed to the formation of modified GA hydrocolloid coating on potato strips with the highest antioxidant capacity (485.3 ± 8.2 TE/100 g) and highest recovery by markers capsaicin, curcumin and linalool. Scanning electron microscope (SEM) photographs confirmed the formation of a rigid (thermal gelation and/or crosslinking) network during frying that has to help cement the cell wall of potato tissue. Furthermore, texture, color and sensory analyses indicated that the proposed GA modified coating had maintained the overall acceptability of DFFPS products.

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6 Consistent clustering of entries in large pairwise comparison matrices 2018-05-17             

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Publication date: 1 December 2018
Source:Journal of Computational and Applied Mathematics, Volume 343

Author(s): J. Benítez, S. Carpitella, A. Certa, A.E. Ilaya-Ayza, J. Izquierdo

In multi-attribute decision making the number of decision elements under consideration may be huge, especially for complex, real-world problems. Typically these elements are clustered and then the clusters organized hierarchically to reduce the number of elements to be simultaneously handled. These decomposition methodologies are intended to bring the problem within the cognitive ability of decision makers. However, such methodologies have disadvantages, and it may happen that such a priori clustering is not clear, and/or the problem has previously been addressed without any grouping action. This is the situation for the case study we address, in which a panel of experts gives opinions about the operation of 15 previously established district metered areas in a real water distribution system. Large pairwise comparison matrices may also be found when building comparisons of elements using large bodies of information. In this paper, we address a consistent compression of an AHP comparison matrix that collapses the judgments corresponding to a given number of compared elements. As a result, an a posteriori clustering of various elements becomes possible. In our case study, such a clustering offers several added benefits, including the identification of hidden or unknown criteria to cluster the considered elements of the problem.





7 Current knowledge of ammonite assemblages from the Štramberk Limestone (Tithonian–lower Berriasian) at Kotouč Quarry, Outer Western Carpathians (Czech Republic) 2018-05-16             

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Publication date: October 2018
Source:Cretaceous Research, Volume 90

Author(s): Zdeněk Vašíček, Petr Skupien, John W.M. Jagt

Forty-two species of perisphinctoid ammonites from the Štramberk Limestone at Kotouč Quarry near Štramberk (Moravia, Czech Republic) have been taxonomically assessed since 2013. Some of these species are contained in old collections at various Moravian-Silesian museums, while others are in the collections of two of us (ZV and PS); all are from Kotouč Quarry. In view of the fact that the Štramberk Limestone usually lacks distinct bedding, the stratigraphical position (ammonite zones) of the taxa identified is derived from literature data. Ammonite species identified document the entire Tithonian to the lower Berriasian. One taxon of early Berriasian age is described as new, Neocosmoceras eliasi. The Tithonian ammonite assemblage, with the exception of the uppermost portion of that stage, is close to those on record from the Mediterranean bioprovince in adjacent countries. In the uppermost Tithonian, a cosmopolitan species, Substeueroceras koeneni, appears. In the lower Berriasian, in addition to Mediterranean representatives, taxa that are known from the Crimean Peninsula and, exceptionally, those from the Subboreal Russian Platform Basin, are present.





8 Spatial comparison of CT-based surrogates of lung ventilation with hyperpolarized Helium-3 and Xenon-129 gas MRI in patients undergoing radiation therapy 2018-05-12             

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Publication date: Available online 10 May 2018
Source:International Journal of Radiation Oncology*Biology*Physics

Author(s): B.A. Tahir, P.J.C. Hughes, S.D. Robinson, H. Marshall, N.J. Stewart, G. Norquay, A. Biancardi, H.-F. Chan, G.J. Collier, K.A. Hart, J.A. Swinscoe, M.Q. Hatton, J.M. Wild, R.H. Ireland

Purpose To develop and apply an image acquisition and analysis strategy for spatial comparison of CT-ventilation images with hyperpolarized gas MRI. Methods 11 lung cancer patients underwent 129Xe and 3He ventilation MRI and co-registered 1H anatomical MRI. Expiratory and inspiratory breath-hold CTs were used for deformable image registration and calculation of three CT-ventilation metrics: Hounsfield unit (CTHU), Jacobian (CTJac) and specific gas volume change (CTSGV). Inspiration CT and hyperpolarized gas ventilation MRI were registered via same-breath anatomical 1H-MRI. Voxel-wise Spearman correlation coefficients were calculated between each CT-ventilation image and its corresponding 3He/129Xe-MRI, and for the mean values in regions of interest (ROIs) ranging from fine to coarse in-plane dimensions of 5x5, 10x10, 15x15 and 20x20, located within the lungs as defined by the same-breath 1H-MRI lung mask. Correlation of 3He and 129Xe-MRI was also assessed. Results Spatial correlation of CT-ventilation against 3He/129Xe-MRI increased with ROI size. For example, for CTHU, mean±SD Spearman coefficients were 0.37±0.19/0.33±0.17 at the voxel-level and 0.52±0.20/0.51±0.18 for 20x20 ROIs, respectively. Correlations were stronger for CTHU than for CTJac or CTSGV. Correlation of 3He with 129Xe-MRI was consistently higher than either gas against CT-ventilation maps over all ROIs (p<0.05). No significant differences were observed between CT-ventilation vs 3He-MRI and CT-ventilation vs 129Xe-MRI. Conclusion Comparison of ventilation-related measures from CT and registered hyperpolarized gas MRI is feasible at a voxel level using a dedicated acquisition and analysis protocol. Moderate correlation between CT-ventilation and MRI exists at a regional level. Correlation between MRI and CT is significantly less than between 3He and 129Xe-MRI, suggesting that CT-ventilation surrogate measures may not be measuring lung ventilation alone.

Teaser

This paper describes: an imaging protocol for acquiring pulmonary CT, 1H, 3He and 129Xe-MRI with similar breath-holds and posture to facilitate accurate spatial comparison of CT-ventilation and hyperpolarized gas ventilation maps via deformable image registration, a validation of CT-ventilation, generated from multi-inflation breath-hold CT, against hyperpolarized gas MRI, a comparison of CT-ventilation against two commonly-used hyperpolarized noble gases (3He and 129Xe) for ventilation imaging, a voxel-wise and ROI-based comparison of CT-ventilation and hyperpolarized gas MRI.



9 Obtaining antimicrobial bilayer starch and polyester-blend films with carvacrol 2018-05-12             

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Publication date: October 2018
Source:Food Hydrocolloids, Volume 83

Author(s): Raquel Requena, María Vargas, Amparo Chiralt

Bilayer films using polyester blends (P) and starch (S) were obtained and characterized, incorporating carvacrol as active compound. Carvacrol was incorporated by spraying it between melt blended and compression moulded sheets or through its incorporation into the chloroform P solution used to obtain P cast films. Different PLA-PHBV ratios (75:25 and 65:35) were tested, with and without 15 wt% of PEG1000, whereas the 75:25 ratio with PEG was only used for cast sheets, based on its better overall properties. Mono and bilayers were characterized as to their tensile and water vapour barrier properties and thermal behaviour. Release kinetics of carvacrol in different food simulants and in in vitro antibacterial activity against Listeria innocua and Escherichia coli were also analysed. Incorporating carvacrol by spraying it between the polyester and starch sheets was not effective at retaining the compound in the bilayers. However, the incorporation of carvacrol into cast P films, and the subsequent formation of bilayers with the S sheets, was highly effective at providing practically total carvacrol retention. These active bilayers exhibited highly improved tensile and water vapour barrier capacity with respect to the S monolayer (87% reduction in WVP, 840% increase in elastic modulus) and inhibited the growth of L. innocua and E. coli from both P or S contact sides of bilayers, depending on the internal diffusion of carvacrol through the bilayer and its adequate release of the compound into the culture medium.

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10 Modifying textural and microstructural properties of low fat Cheddar cheese using sodium alginate 2018-05-11             

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Publication date: October 2018
Source:Food Hydrocolloids, Volume 83

Author(s): Bal Kumari Sharma Khanal, Bhesh Bhandari, Sangeeta Prakash, Dasong Liu, Peng Zhou, Nidhi Bansal

Low fat Cheddar cheese (LFC) with up to 91% fat reduction were prepared using four levels of sodium alginate (alginate): 0.12 (LFCA1), 0.17 (LFCA2), 0.18 (LFCA3) and 0.23% (w/w) (LFCA4). Control full fat cheese (CFFC) and control low fat cheese (CLFC) were used for comparison. Physical characteristics, namely texture profile, microstructure, transverse relaxation time (T2) distribution (measured by low-field NMR) and color were analysed periodically during ripening until 180 days. Texture profile analysis illustrated a significant improvement in texture of alginate added LFC (P < 0.05) as compared to CLFC. The textural attributes of LFCA1 ripened for 30 days were comparable to CFFC ripened for 60 days and beyond. A close resemblance in textural attributes between alginate added LFC and CFFC, not previously reported when using other fat replacers, was observed. Scanning electron micrograph (SEM) images revealed that alginate added LFCs had smoother surfaces as compared to CFFC and CLFC, and the dense and compact protein matrix characteristic of CLFC was not observed. Confocal laser scanning microscopy (CLSM) suggested that the fat particle size, area and volume were affected in all LFCs due to their lower fat level and these parameters increased during ripening in CFFC. NMR results revealed increase in higher mobility water fraction in alginate added cheese compared to CFFC and CLFC. Hunter L, a and b values for alginate added LFCs indicated that they were whiter than CLFC and less yellowish than CFFC at the beginning of ripening; the color of some of the alginate added LFCs was comparable to CFFC after 120 days of ripening. Overall, addition of alginate significantly improved the textural, microstructural properties and color of LFCs, affirming its potential as a promising texture modifier.

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