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|1 || Quantifying the differences in structure and mechanical response of confectionery products resulting from the baking and extrusion processes
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Publication date: December 2018
Source:Journal of Food Engineering, Volume 238
Author(s): Saba S. Butt, Idris K. Mohammed, Vivek Raghavan, James Osborne, Hugh Powell, Maria N. Charalambides
Extrusion has potential advantages over baking in terms of throughput, asset cost and flexibility. However, it is challenging to achieve through extrusion the “light, crispy” texture of a more traditional baked confectionery. This study compares and contrasts for the first time confectionery products produced through these two processes, i.e. baking and extrusion. The microstructural differences are measured using imaging techniques, i.e. Scanning Electron Microscopy (SEM) and X-Ray Tomography (XRT) whereas mechanical characterisation is used to highlight differences in the resulting mechanical properties. Crucial information is presented which shows that the two technologies result in different mechanical properties and microstructures, even if the level of porosity in the two products is kept constant. In addition, confectionery products whether they are produced through baking or extrusion, have irregular geometries. The latter makes mechanical characterisation a real challenge. Therefore this study also presents rigorous methods for measuring true mechanical properties such that meaningful and valid comparisons may be made. The accuracy of the chosen methodologies is verified through experiments using flat and tubular extruded geometries as well as testing the products in various directions. It was concluded that the manufacturing method and, in the case of extrusion, the initial moisture content influences the microstructure and mechanics of confectionery products, both of which have an impact on consumer sensory perception.
|2 || Localization of dynamic forces on structures with an interior point method using group sparsity
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Publication date: 15 January 2019
Source:Mechanical Systems and Signal Processing, Volume 115
Author(s): J. Wambacq, K. Maes, A. Rezayat, P. Guillaume, G. Lombaert
This paper presents an algorithm for the localization of forces applied to a structure. The force estimation is performed in the frequency domain based on a limited number of sensors and a linear dynamic system model and it involves minimizing an objective function penalized with a group sparsity term. The minimization of this objective function is formulated as a second order cone program, which is solved using an interior point method. This allows for a reduction of the calculation time when compared to other algorithms that are currently available to enforce group sparsity on the forces, especially for large scale problems. The presented algorithm is first verified using numerical simulations. Next, a validation is performed using data obtained from a field test on a footbridge, where two locations on the bridge deck are excited using hammer impacts and the force localization is performed assuming a total of 108 possible force locations.
|3 || Correlation of Regional Lung Ventilation and Gas Transfer to Red Blood Cells: Implications for Functional-Avoidance Radiation Therapy Planning
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Publication date: Available online 14 April 2018
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Leith J. Rankine, Ziyi Wang, Bastiaan Driehuys, Lawrence B. Marks, Chris R. Kelsey, Shiva K. Das
Purpose To investigate the degree to which lung ventilation and gas exchange are regionally correlated, using the emerging technology of hyperpolarized (HP)-129Xe magnetic resonance imaging (MRI). Methods and Materials Hyperpolarized-129Xe MRI studies were performed on 17 institutional review board–approved human subjects, including 13 healthy volunteers, 1 emphysema patient, and 3 non-small cell lung cancer patients imaged before and approximately 11 weeks after radiation therapy (RT). Subjects inhaled 1 L of HP-129Xe mixture, followed by the acquisition of interleaved ventilation and gas exchange images, from which maps were obtained of the relative HP-129Xe distribution in three states: (1) gaseous, in lung airspaces; (2) dissolved interstitially, in alveolar barrier tissue; and (3) transferred to red blood cells (RBCs), in the capillary vasculature. The relative spatial distributions of HP-129Xe in airspaces (regional ventilation) and RBCs (regional gas transfer) were compared. Further, we investigated the degree to which ventilation and RBC transfer images identified similar functional regions of interest (ROIs) suitable for functionally guided RT. For the RT patients, both ventilation and RBC functional images were used to calculate differences in the lung dose–function histogram and functional effective uniform dose. Results The correlation of ventilation and RBC transfer was ρ = 0.39 ± 0.15 in healthy volunteers. For the RT patients, this correlation was ρ = 0.53 ± 0.02 before treatment and ρ = 0.39 ± 0.07 after treatment; for the emphysema patient it was ρ = 0.24. Comparing functional ROIs, ventilation and RBC transfer demonstrated poor spatial agreement: Dice similarity coefficient = 0.50 ± 0.07 and 0.26 ± 0.12 for the highest-33%- and highest-10%-function ROIs in healthy volunteers, and in RT patients (before treatment) these were 0.58 ± 0.04 and 0.40 ± 0.04. The average magnitude of the differences between RBC- and ventilation-derived functional effective uniform dose, fV20Gy, fV10Gy, and fV5Gy were 1.5 ± 1.4 Gy, 4.1% ± 3.8%, 5.0% ± 3.8%, and 5.3% ± 3.9%, respectively. Conclusion Ventilation may not be an effective surrogate for true regional lung function for all patients.
|4 || Streamline-averaged mass transfer in a circulating drop
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Publication date: 23 November 2018
Source:Chemical Engineering Science, Volume 190
Author(s): Paul Grassia, Sebastián Ubal
Solute mass transfer is considered from the outside to the inside of a circulating drop in the context of liquid-liquid extraction. Specifically an internal problem is treated with resistance to mass transfer dominated by the liquid inside the drop. The Peclet number of the circulation is large, on the order of tens of thousands. A model is proposed by which the mass transfer into the drop begins in a boundary layer regime, but subsequently switches into a so called streamline-averaged regime. Solutions are developed for each regime, and also for the switch between them. These solutions are far easier to obtain than those of the full advection-diffusion equations governing this high Peclet number system, which are very stiff. During the boundary layer regime, the rate at which solute mass within the drop grows with time depends on Peclet number, with increases in Peclet number implying faster growth. However larger Peclet numbers also imply that the switch to the streamline-averaged regime happens sooner in time, and with less solute mass having been transferred to date. In the streamline-averaged regime, solute concentration varies across streamlines but not along them. In spite of the very large Peclet number, the rate of mass transfer is controlled diffusively, specifically by the rate of diffusion from streamline-to-streamline: sensitivity to the Peclet number is thereby lost. The model predictions capture, at least qualitatively, findings reported in literature for the evolution of the solute concentration in the drop obtained via full numerical simulation.
|5 || Rational design of sensor for broadband dielectric spectroscopy of biomolecules
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Publication date: 10 November 2018
Source:Sensors and Actuators B: Chemical, Volume 273
Author(s): Daniel Havelka, Ondrej Krivosudský, Jiří Průša, Michal Cifra
Knowledge of electromagnetic properties of biomolecules is essential for a fundamental understanding of electric field interaction with biosystems and for development of novel biomedical diagnostic and therapeutic methods. To enable systematic analysis of the dielectric properties of biomolecule solutions we presented here a method for a rational design of radiofrequency and microwave chip for quantitative dielectric sensing. At first, we estimated the primary frequency band of interest using a relaxation time of targeted molecule via the Stokes–Einstein–Debye equation. Then we proposed a microwave sensing chip for the estimated frequency band and evaluated its performance using both analytical modeling and numerical electromagnetic simulations. We fabricated the chip and experimentally demonstrated that we can extract the complex permittivity (0.5–40 GHz) of the water solution of alanine – one of the most common proteinogenic amino acids – without any calibration liquid and with about 20-fold smaller volume than with commercial methods. The observed dependence of extracted complex permittivity on the alanine concentration was interpreted using molecular dynamics simulations. The procedure we described here can be applied for the development of dielectric sensing method of any polar biomolecule solution.
|6 || Multi-output efficiency and operational safety: An analysis of railway traffic control centre performance
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Publication date: 16 November 2018
Source:European Journal of Operational Research, Volume 271, Issue 1
Author(s): Bart Roets, Marijn Verschelde, Johan Christiaens
Transportation service providers are under increasing pressure to raise cost efficiency without sacrificing safety. We show the usefulness of a nonparametric multi-output framework to both monitor staff efficiency and detect operational safety concerns. To realistically model input–output relations at an hourly rate of Belgian computerized railway traffic control centres, we apply a Data Envelopment Analysis (DEA)-based framework with proportional cost allocation restrictions and introduce output-specific metafrontiers. Our analysis (covering each single hour of the complete year 2015) shows that production tasks with a highly variable work load, when characterized by binding cost allocation restrictions and high within-traffic-control-centre efficiency, are more prone to human error. Further, we show how DEA combined with disaggregated data can be used to a priori assess staff schedule changes.
|7 || A general objective shock wave detection from a geometric singular perturbation approach
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Publication date: January 2019
Source:Communications in Nonlinear Science and Numerical Simulation, Volume 66
Author(s): Z. Wang, J. Zhang, L. Wang, Y. Liu
For the general unsteady multi-dimensional flow, the non-linear non-equilibrium nature of shock waves is investigated from the geometric singular perturbation theory. With the introduction of a pressure non-equilibrium term, the modified Euler equation can be reduced to systems of ordinary differential equations(ODEs) along carefully constructed curves. Along each curve, a slow-fast system is derived from the governing ODEs, and the geometric singular perturbation theory is then applied. The motion of the slow-fast system is decomposed to two parts, the quasi-equilibrium slow motion where the non-equilibrium effect is negligible and the fast motion where the non-equilibrium effect plays a dominating role. It is then shown that a shock wave can be recognized as the fast motion of a slow-fast system in an objective manner, and this shock detection method can serve as a rational foundation for practical shock detection problem.
|8 || Structural, electronic, vibrational, optical and thermodynamic properties of 3-Oxo-3-p-tolylpropylphosphonic acid and 4-Oxo-4-p-tolyl-butyric acid: Density functional theory study
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Publication date: 5 November 2018
Source:Journal of Molecular Structure, Volume 1171
Author(s): Abdelkader Hellal, Djebaili Rachida, Samia Zaout, Mouna Elkolli, Salah Chafaa, Lasnouni Touafri, Nadjib Chafai, Mouna Mehri, Khalissa Benbougerra
Two analog acids, once is phosphonic acid, 3-Oxo-3-p-tolylpropylphosphonic acid, and the other is carboxylic acid, 4-Oxo-4-p-tolyl-butyric acid have been studied from a theoretical point of view in order to know their electronic, vibrational and thermodynamic properties by means of Density Functional Theory (DFT) calculations. The stable structures were optimized by using the hybrid B3LYP/6-31G method. The different proprieties for both compounds were analysed by means of the HOMO-LUMO proprieties, atomic charges, dipole moments, molecular electrostatic potentials and thermodynamic parameters. The vibrational spectra of the two acids are calculated and compared with those obtained with experimental FTIR method. The reactivity of molecules using various descriptors such us local softness, electrophilicity, electronegativity, hardness, HOMO-LUMO gap etc. are calculated and discussed.
|9 || 13C → 1H transfer of light-induced hyperpolarization allows for selective detection of protons in frozen photosynthetic reaction center
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Publication date: August 2018
Source:Journal of Magnetic Resonance, Volume 293
Author(s): Pavlo Bielytskyi, Daniel Gräsing, Kaustubh R. Mote, Karthick Babu Sai Sankar Gupta, Shimon Vega, P.K. Madhu, A. Alia, Jörg Matysik
In the present study, we exploit the light-induced hyperpolarization occurring on 13C nuclei due to the solid-state photochemically induced dynamic nuclear polarization (photo-CIDNP) effect to boost the NMR signal intensity of selected protons via inverse cross-polarization. Such hyperpolarization transfer is implemented into 1H-detected two-dimensional 13C–1H correlation magic-angle-spinning (MAS) NMR experiment to study protons in frozen photosynthetic reaction centers (RCs). As a first trial, the performance of such an experiment is tested on selectively 13C labeled RCs from the purple bacteria of Rhodobacter sphaeroides. We observed response from the protons belonging to the photochemically active cofactors in their native protein environment. Such an approach is a potential heteronuclear spin-torch experiment which could be complementary to the classical heteronuclear correlation (HETCOR) experiments for mapping proton chemical shifts of photosynthetic cofactors and to understand the role of the proton pool around the electron donors in the electron transfer process occurring during photosynthesis.
|10 || Synthesis of luminescent CePO4:Tb/Au composite for glucose detection
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Publication date: December 2018
Source:Dyes and Pigments, Volume 159
Author(s): Guanwen Yan, Yuan Zhang, Weihua Di, Weiping Qin
The glucose oxidase (GOx) is commonly used as targeting molecule for glucose detection since a specific enzymatic reaction can occur, namely, catalytic oxidation of glucose by GOx. However, the intrinsic denaturation of natural enzyme is a problem in the use that leads to the detection inaccuracy and unstability. Here, we designed and prepared the luminescent CePO4:Tb/Au composite for glucose sensing, in which small-sized Au nanoparticles possess GOx-mimicking activity for catalytic oxidation of glucose and the in situ generated H2O2 quenches the luminescence of CePO4:Tb, enabling the fluorescent detection of glucose. The quenching of luminescence in dilute solutions can be well described by the Stern-Volmer relationship in a wide analyte concentration range with the Ksv quenching constant of 13070 M−1. A detection limit of 5.25 μM and a good sensing selectivity were achieved. More importantly, the problem of unstability using natural enzyme in the glucose determination can be efficiently solved by using Au as catalyst instead of GOx due to long-term preserved catalytic activity of Au. Therefore, our developed fluorescent system for glucose detection is potential in the biochemical analysis.
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