131,083 research outputs found
A mass spectrometry approach to dairy science
No full textBovine milk is a source of an array of (un)known (bioactive) compounds from a variety of molecular and chemical classes. Because of a such complex food matrix, accurate and sensitive analytical approaches are needed to identify newly formed molecules (e.g. bioactive milk non-nutrients or xenobiotics), to recognize chemical and enzymatic modifications which known milk components undergo upon processing, storage and in vitro digestion. In this perspective, tailored sample preparation followed by liquid chromatography/high resolution mass spectrometry (LC/HR-MS) represents a powerful analytical tool to solve some scientific issues in dairy sector. In this presentation, some of the current applications of MS in dairy science will be discussed with special regard to characterization of novel functional/(bio)active milk compounds [1], reliable identification of dairy markers (e.g. studying post-translational modifications [2], proteolytic phenomena [3–6], identification of bioactive non-nutrients [7–9]), traceability and confirmation of authenticity [10] of dairy products.
[1] M. Stuknytė, S. Cattaneo, F. Masotti, I. De Noni, Food Chemistry, 168, 27–33 (2015)
[2] S. Cattaneo, F. Masotti, L. Pellegrino, Journal of Agricultural and Food Chemistry, 57, 10689–10694 (2009)
[3] S. Cattaneo, M. Stuknytė, L. Pellegrino, I. De Noni, Food Chemistry, 155, 179–185 (2014)
[4] F. Masotti, I. De Noni, S. Cattaneo, M. Brasca, V. Rosi, M. Stuknyte, S. Morandi, L. Pellegrino, International Dairy Journal, 33, 90–96 (2013)
[5] F. Masotti, J. A. Hogenboom, V. Rosi, I. De Noni, L. Pellegrino, International Dairy Journal, 20, 352–359 (2010)
[6] S. Cattaneo, J. A. Hogenboom, F. Masotti, V. Rosi, L. Pellegrino, P. Resmini, Dairy Science and Technology, 88, 595–605 (2008)
[7] V. Taverniti, M. Stuknyte, M. Minuzzo, S. Arioli, I. De Noni, C. Scabiosi, Z. Martinez Cordova, I. Junttila, S. Hämäläinen, H. Turpeinen, D. Mora, M. Karp, M. Pesu, S. Guglielmetti, Applied and Environmental Microbiology, 79, 1221–1231 (2013)
[8] I. De Noni, S. Cattaneo, Food Chemistry, 119, 560–566 (2010)
[9] I. De Noni, Food Chemistry, 110, 897–903 (2008)
[10] R. Russo, V. Severino, A. Mendez, J. Lliberia, A. Parente, A. Chambery, Journal of Mass Spectrometry, 47, 1407–1414 (2012
A Novel 3-D Printed Dual-Port Rectenna for Simultaneous Energy Harvesting and Backscattering of a Passively Generated UWB Pulse
No full textThis work presents the design and characterization of a new compact rectenna system, fully three-dimensional (3-D) printed on a low-cost material, the polylactic acid (PLA). The rectenna consists of a patch-like antenna, with two orthogonal excitation ports, suitably designed to achieve both ultra-high-frequency (UHF) and ultra-wideband (UWB) cross-polarized radiation performance. The first port harvests multi-tone RF power at UHF, around 2.47 GHz (for the present case 8 equally spaced non-synchronized tones are used); the second port backscatters the intermodulation (IM) products generated by the rectifier, realizing a quasi-UWB pulse. The rectifier consists of a single-diode embedded into two linear subnetworks: one, connecting the UHF port and the diode, is co-designed to ensure dc-block and rectifier-antenna matching in the UHF band; the second one combines a high-pass filter, connecting the diode and the UWB port, to backscatter the passive pulse, and a dc path to collect the converted dc power. The 3-D etching of the low-cost substrate is optimized to obtain antenna performance comparable to those achieved with specialized RF materials. The system design is carried out by integrating full-wave and nonlinear simulations with the manifold goal of minimizing the overall footprint, ensuring UWB-mask-compatible radiated spectra and RF-to-dc conversion efficiency. A 3-D printed prototype has been realized and experimentally characterized. With a total received power of -15 dBm, equally distributed over eight tones spaced by 1 MHz, a quasi-UWB pulse power peak of about 80 nW has been demonstrated
Innovative 3-D Printing Processing Techniques for Flexible and Wearable Planar Rectennas
No full textThis work demonstrates the use of a low-cost, lossy, flexible substrate processed by novel 3-D printing techniques which significantly mitigate its intrinsic losses, thus providing performance comparable to those of traditional substrates. These processing techniques are applied to both microstrip and coplanar waveguide structures; they are first derived theoretically, starting from the electromagnetic theory of modes propagation, then numerically validated by full-wave analysis, and finally experimentally verified. The design of a miniaturized 868 MHz rectenna, adopting a coplanar-fed patch antenna based on the proposed fabrication approach, is presented. By means of nonlinear/electromagnetic co-design, the antenna is directly matched to the rectifier. A 30-dB power range starting from -20 dBm is considered. Direct matching allows to get rid of a dedicated matching network and its associated losses, resulting in a slight efficiency increase and a significant reduction of the overall dimensions. Finally, the 3-Dprinted prototype is presented: the overall rectenna performance proves that design freedom enabled by 3-D printing paves the way to the use of low-cost flexible dielectric materials, even with poor electromagnetic properties, to realize wearable battery-free wireless nodes
Measurement of Time-Based Arrays for Massive Tags Localization
No full textThe paper describes a time-based driving strategy of a compact antenna array suitable for future 5G IoT applications. Array elements are selectively activated in real-time for agile localization of and energy transfer to tagged objects, randomly distributed in harsh electromagnetic environments. The exploitation of time-modulation technique allows to simultaneously radiate at both the carrier frequency and the sideband harmonics due to the superposition of the nonlinear switches driving (or modulation) frequency. These arrays result in a very simple architecture if compared to standard arrays. Despite this, their characterization is not straightforward: in this paper some preliminary measurements of a two-element array for localization purposes are presented
3-D Etching Techniques for Low-Cost Wearable Microwave Devices in Grounded Coplanar Waveguide
No full textThis work presents a new, 3D-printed design for grounded coplanar waveguide (GCPW), employing a low-cost, flexible substrate for wearable microwave applications. First, a resonant technique is used to derive the electromagnetic characteristics of the selected material, Flexible 80A, which is highly flexible but lossy. Next, to use this material as the GCPW substrate, novel fabrication techniques are analyzed to minimize the losses, based on customized removals of the material from the aperture regions, to reduce dispersion and minimize propagation loss. The first results show that the proposed techniques outperform both traditional microstrip and GCPW technologies and promise to be an excellent solution for the 3-D printing of low-cost flexible/wearable tags/sensors that can be activated wirelessly
Ad-hoc WPT Exploiting Multi-sine Excitation of Linear Frequency Diverse Arrays
No full textIn this work an effective solution for real-time focusing of frequency diverse arrays (FDAs) is proposed, to be exploited for intentional far-field wireless power transfer (WPT) applications. With respect to the literature where improved focusing capabilities of the traditional linear (1-D) FDAs are achieved at the expense of frequency distributions following non-linear rules (e.g., logarithmic) or complex 2-D arrangements of the transmitting architecture (e.g., concentric circular distribution), the proposed solution provides the best performance with a simpler transmitting layout. In fact, this technique proposes a multi-sine excitation for each radiating element: in this way the performance in terms of dimension of the radiated beam are improved, avoiding the well-known and critical 'S-shape' of the beampattern (BP) that is useful for radar and localization application, but not for precise and ad-hoc smart WPT. The mathematical model able to fully describe the radiation properties of the multi-sine frequency diverse array (MSFDA) is presented and the unprecedented capabilities, in terms of power focusing and ease of design, are demonstrated. MSFDA is thus proposed as an excellent solution for far-field precise WPT able to avoid sensible targets when powering: this is obtained by moving the complexity from the antenna design to the signal generation block, where advanced and sophisticated systems as software defined radio (SDR) are envisaged
Start-up solutions for ultra-low power RF harvesting scenarios
No full textThis paper is an overview of important results obtained by our research group in the field of computer-aided-design of highly efficient RF energy harvesters. Particular attention is devoted to start-up strategies for ultra-low power scenarios: an integrated DC-DC converter, with start-up and maximum power point tracking functionalities, as actual load of the rectenna, shows a fully autonomous operation; a dual-branch rectenna with switched-load rectifiers significantly reduces the available RF power levels able to wake-up the system, despite of the discrete components employed. The obtained performance demonstrate, both for off-the-shelf discrete solutions and customized integrated ones, that a rigorous design approach is mandatory, especially when extremely low power budget are involved
A New Wheel-Spoke Transmitter for Efficient WPT Based on Frequency Diversity
No full textIn this work an effective and feasible solution at
millimeter-wave for real-time focusing of Frequency Diverse
Arrays (FDAs) is proposed, to be exploited for intentional farfield Wireless Power Transfer (WPT) applications. A confined
and precise spot to concentrate the power is obtained by a novel
3-D multi-layer wheel-spoke like array of patch antennas,
exploiting circular symmetry, directly connected with microstrips
through metallized via holes. The system is theoretically
developed and numerically demonstrated by the full-wave
analysis of the realistic layout of 32-element, wheel-spokearranged FDA with a center frequency of 24 GHz. The simulated
results of the realistic layout demonstrate that this solution offers
unprecedent capabilities in terms of power focusing and ease of
design, with respect to the state-of-the-art. Preliminary
measurements of the wheel-spoke transmitter are provided for
validation of the adopted feeding technique based on direct
connection between microstrips and patches through metallized
via hole arranged in circular symmetr
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