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Metabolite annotation from imaging mass spectrometry (imaging MS) data is a difficult undertaking that is extremely resource intensive. Here, we adapted METASPACE, cloud software for imaging MS metabolite annotation and data interpretation, to quickly annotate microbial specialized metabolites from high-resolution and high-mass accuracy imaging MS data. Compared with manual ion image and MS1 annotation, METASPACE is faster and, with the appropriate database, more accurate. We applied it to data from microbial colonies grown on agar containing 10 diverse bacterial species and showed that METASPACE was able to annotate 53 ions corresponding to 32 different microbial metabolites. This demonstrates METASPACE to be a useful tool to annotate the chemistry and metabolic exchange factors found in microbial interactions, thereby elucidating the functions of these molecules. ispartof: METABOLITES vol:11 issue:8 ispartof: location:Switzerland status: published

This paper proposes an extensive study of multisine excitations to enable high-accuracy localization of battery-less tags, by harvesting the higher order harmonics, generated by the rectifier nonlinearity. Usually, these harmonics are either filtered out or terminated, to increase the conversion efficiency. A dual-mode rectifier with the output section splitted into two paths is designed. One dc path is the common one used to deliver the converted dc power to an optimum load and the second path is broadband and collects the higher harmonics obtaining an ultrawideband radiated signal to communicate with the receivers for tag localization. To this purpose, a variety of multisine excitation signals, with different tones, spacing among tones and bandwidth, is accurately evaluated to characterize the system-level localization performance. Both the modeled and experimental results are presented demonstrating the excellent performance of such a dual-mode rectifier, despite of the limited add-on circuitry if compared to those used in standard rectennas. For an average received power of -10 dBm, measurements show that the localization of a tag with centimeter-level accuracy can be achieved at more than 10 m distance from the receivers having a 4 dB noise figure.

This paper introduces a novel solution for portable devices to exploit their existing communication antennas for bi-directional near-field wireless re-charging, without compromising their far-field properties. To demonstrate the concept, the radio-frequencies (RF) 900/1800 MHz and 433 MHz are adopted for the far-field communication and for the near-field wireless recharging, respectively. First, a pair of faced, dual-band, printed monopoles is characterized as a two-port network over the bands of interest at several distances. Then, each antenna is fed by a frequency-selective three-port network, designed to simultaneously ensure data communication at the higher frequencies and wireless re-charging at the lower one. In this way, the combined far-field and near-field operations of the resulting four-port network can be optimized. A proof-of-concept prototype has been characterized, showing ports isolation higher than 20 dB and RF-to-RF power transfer efficiency between 15% and 40% for variable faced antennas distance. When a rectifier is connected to the receiving power port, the measured RF-to-dc link efficiency varies between 9% and 20%, with portable devices located 1 and 2 centimeters apart, and the transmitted power is 10 dBm. The simultaneous high frequency communication is verified with slightly reduced performance.

To enable pervasive exploitation of wireless sensor networks (WSNs), semi-passive wake-up radios (WuR) are proposed to minimize the active time of the energy-hungry main communication radio. The most challenging feature is to enhance their sensitivity, the weakest activation signal the receiver is able to sense, that is limited by the minimum turn-on voltage of diode-based detector. In order to operate the detector at even lower power levels, a strategy to optimize the modulated WuR excitations is presented, exploiting high-peak intermittent continuous waves (ICW), while preserving the required average power per bit. The design and implementation of an ultra-low-power detector, fed by a dual-band antenna and loaded by the WuR back-end is presented: 2.45-GHz and 868-MHz operations of the same WuR are demonstrated, with added flexibility and interoperability among different communication bands. We show that a correct WuR activation is possible with an average power per bit as low as -63 dBm at 2.45 GHz and -65 dBm at 868 MHz. This is experimentally verified by a lab-level set-up and confirmed by a system implementation based on off-the-shelf components only.

This paper proposes a smart wireless power transmission method, based on a two-step procedure, exploiting real-time beaming of time-modulated arrays. The sideband radiation phenomenon, which is usually a drawback of these radiating systems, is favorably used for intentional wireless power transfer (WPT): in a first step to precisely localize the tag to be powered and in the second one to perform directive WPT. The approach is first theoretically discussed, then the numerical procedure, which integrates full-wave analysis of the antenna array with nonlinear simulation of the modulated nonlinear feeding network, is used to validate the principle of operation and to include nonlinearities and electromagnetic couplings affecting the whole system performance. The procedure allows a flexible design of the time-modulated-array-based WPT system, taking into account the impact of different array elements layout and spacing on localization and power transmission performance. Experiment of the first step is carried out in a real indoor environment at 2.45 GHz: a TI MSP430 drives a Schottky-diode-based network to provide proper modulated RF excitations of the array elements. Measurements show that the system is able to select tags to be energized randomly distributed in a 100 $^{\circ}$ -scanning range.

This paper proposes the use of multi-sine UHF excitation for rectenna applications not only for the well-known possible improvement of rectification performance in energy harvesting, but also for exploiting the same rectifier to enable high-accuracy localization of the tag by backscattering higher order harmonics usually wasted and unwanted. This twofold goal is obtained through the design of an extremely simple dual-mode RFID tag, exploiting the multi-sine UHF excitation to harvest energy, and the UWB signal, generated for free and consisting of the higher intermodulation products, to communicate with the readers for the tag itself localization. Both modeled and measured results demonstrate the excellent dual-mode performance, despite of the limited add-on circuitry if compared to other tags architectures combining energy harvesting and localization capabilities.

A UHF energy harvesting unit, also comprising UWB communication function, is integrated in a low-profile, compact, unique device. The optimized collocation of two couples of dual linearly-polarized dipoles provides all-polarization receiving capability and a quasi-isotropic radiation, momentous features for RF energy harvesting applications. Activation distance of a commercial ultra-low power management unit is enhanced with respect to a corresponding single-rectenna case. The EM-based non-linear simulation of the entire system has shown its ability to rectify RF power incident from any direction, with activation distances always higher than 14.7 meters for any direction of arrival and up to 26 meters in the best-case condition. Im-plementation of the presented RF harvester outperforms the cor-responding single-dipole harvester realization in a real indoor scenario

This paper reviews the most recent methods, combining nonlinear harmonic-balance-based analysis with electromagnetic (EM) simulation, for optimizing, at the circuit level, modern radiative RF/microwave systems. In order to maximize the system efficiency, each subsystem must be designed layoutwise, accounting for the presence of the others, that is, accounting for its actual terminations, rather than the ideal ones ( $50~\Omega$ ). In this way, the twofold goal of minimizing size and losses of the system is obtained by reducing intersystem matching networks. Indeed, terminations are complex, frequency-dispersive, and variable with the signal level, if active operations are concerned, and are responsible for performance degradation if not properly optimized. This approach is nowadays necessary, given the ever increased spread of pervasively distributed RF microsystems adopting miniaturized antennas, such as radio frequency identification (RFID) or wireless sensor networks, that must be low-cost, low-profile, low-power, and must simultaneously perform localization, identification, and sensing. For the design of a transmitter and a receiver connected with the respective antennas, suitable figures of merit are considered, encompassing radiation and nonlinear performance. Recent representative low-profile realizations, adopting ultra-wideband (UWB) excitations are used to highlight the benefit of the proposed nonlinear/EM approach for next generation energy autonomous microsystem, such as UWB-RFID tags.

none 11 si In the new scenarios foreseen by the Internet of Things (IoT), industrial and consumer systems will be required to detect and localize tagged items with high accuracy using cheap, energy autonomous, and disposable tags. This paper discusses system-level and circuit-level aspects to be adopted for future generation passive RFID tags with localization capabilities. It is argued that RFID-enabled localization strategies, combining UWB backscattering for communication/ localization purposes and UHF for “on demand” powering of battery-less tags can be successfully exploited to this purpose. The proposed architecture adopts a small number of reference nodes, acting both as UWB readers and as UHF power sources. Architectural and circuital considerations on different design choices for the UWB-RFID tag are discussed, focusing on available off-the-shelf components. Power budget constraints for UWB backscattering operation and UHF wireless powering are derived in worst-case conditions. Furthermore, the simulation results, verified with experiments, proof the feasibility of cm-level localization accuracy at distances of several meters even in indoor scenarios where multi-path fading might be present. Costanzo, Alessandra; Dardari, Davide; Aleksandravicius, Jurgis; Decarli, Nicolo; Del Prete, Massimo; Fabbri, Davide; Fantuzzi, Marco; Guerra, Anna; Masotti, Diego; Pizzotti, Matteo; Romani, Aldo Costanzo, Alessandra; Dardari, Davide; Aleksandravicius, Jurgis; Decarli, Nicolo; Del Prete, Massimo; Fabbri, Davide; Fantuzzi, Marco; Guerra, Anna; Masotti, Diego; Pizzotti, Matteo; Romani, Aldo

The development of distributed and ubiquitous electronic devices is an achievement of modern technology that has the potential to revolutionize many aspects of human life. Such electronic devices are being employed not only in consumer areas like home automation, intelligent transportation systems, and personal entertainment but also for health-care applications, such as noninvasive biomedical parameter monitoring, as well as industrial and military applications.

As the population lives longer, more and more individuals are diagnosed with age-related illnesses and need to be monitored and assisted continually, possibly at home. Evidence proves that the examination of high-risk patients' movements and behavior can help the early detection of disorders such as Alzheimer's disease or major depression. In this contribution we describe the exploitation of a 2.45 GHz RFID reader, augmented with the RADAR-monopulse capabilities for accurate and fast beam-steering, to simultaneously locate and track a number of tagged entities (objects or people) static or moving, widely distributed in an harsh electromagnetic (EM) environment. In this way long-term people movements and ambient occupancy can be accurately evaluated in typical room ambient, both residences and nursing homes. The proposed system is able not only to detect the angular position of people but also to estimate their distance from the reader with centimeter accuracy. This information can be collected and adopted for various uses by the family members or by the medical team to assist with early diagnosis and care.

To minimize energy consumption of state-of-the-art wireless sensor nodes, asynchronous communication transceivers are adopted, which make use of an ultra-low power wake-up radio (WUR) to minimize the active time of the energy-hungry main communication radio. This work contributes to the ambitious goal of pushing over the minimum average RF power needed to operate the WUR, thus enabling energy-efficient communication in larger areas. To reach this goal a dual-band rectifier, optimized to be loaded by an ultra-low power comparator, is used as WUR detector. Its behavior is experimentally tested under several power-optimized excitation formats. By selecting the proper excitation format the base-band comparator is enabled starting from average RF-power as low as -64.5 dBm.

Wake-up radio is an emerging technology for smart sensor networks and the Internet of Things with the ambitious goal of minimizing the power needed to communicate, thus enabling a new generation of applications. Wake-up radios should exhibit low latency coupled with high sensitivity, addressing capabilities with ultra-low power budget. They may be combined with existing radio transceivers and power management units to reduce the overall communication power while maintaining a high performance. This paper presents a 2.45 GHz and 868 MHz wake-up radio with the above mentioned characteristics. Dual band is exploited to increase the flexibility of the wakeup radio, allowing interoperability with the two most common bands used in Wireless Sensors Network and Internet of Things. Simulations results present a system with sensitivity as low as -55 dBm at 868 MHz and -53 dBm at 2.45 GHz.

This work demonstrates a novel 2.45-GHz bi-directional circuit that can operate as both a wireless power transmitter and energy harvester. The circuit is based on a class-F oscillator/rectifier and is energy-autonomous since it does not need an external bias supply for either power transmission or power reception. Bi-directionality is exploited in two steps: the system first operates in rectifying mode with harvested DC voltages for biasing the oscillator; followed by the transmitting mode where the harvested DC power is used to start up oscillations. Conversion efficiencies for both configurations are higher than 50% for output/input RF power in the 10dBm range. This component can be exploited as a “power relay node” for distributed battery-less energy autonomous microsystems.

This paper describes the design and experimental characterization of a battery-less bidirectional 2.45-GHz circuit operating in oscillator mode as a wireless power transmitter or in rectifier mode as an energy harvester, with a measured efficiency greater than 50% in both operating states. The dc voltage harvested in rectifier mode provides the drain bias for the oscillator. The FET-gate self-bias mechanism is exploited in both functionalities, thus eliminating external gate bias. Bi-directionality is based on the time-reversal properties of a transistor oscillator. Energy autonomy is possible at received RF power levels as low as ${-}4$ dBm, by means of a bias-assisting feedback loop, consisting of a single matched low-power diode in shunt configuration. A hybrid prototype is demonstrated with the ability to operate as an energy-autonomous power relay node by switching between transmit and receive power modes.

The same antenna, designed to exploit its far-field properties for communication purposes, can be suitably configured for simultaneously realizing wireless power transfer via its near-field properties. In this paper we analyze the near-field behavior of a pair of closely coupled transmitting and receiving dual-band printed monopole antennas, suitable for cell phones applications. The proposed architecture is based-on a frequency division approach, operating in the GSM900 and GSM1800 bands for data communications, and in the ISM 433 MHz for near-field power transfer. In this work we develop the theoretical and numerical demonstration of how it is possible to achieve both far-field performance and near-field power transfer efficiency (from 35% to 10%) for mobile phones located few centimeters apart.

In this paper we exploit genetic algorithms to design a rectenna required to harvest ambient radio-frequency (RF) energy from four different RF bands in critical (ultra-low power) conditions. For this purpose a set of multi-resonant annular-ring patch antennas are pixel-wise described inside an electromagnetic (EM) simulator to provide the “population” of individuals among which the genetic tool is able to select the most adapted one with respect to the design specifications. The further use of circuit-level nonlinear simulation tool, based on Harmonic Balance (HB) technique, allows the rigorous multi-band design of the whole rectenna system in RF stationary conditions at several received power levels. The result is a novel compact, lightweight, and highly efficient tetra-band rectenna, able to harvest RF energy from GSM 900, GSM 1800, UMTS and WiFi sources available in the ambient. At these frequency bands high radiation efficiency is desired as an essential prerequisite for optimally handling very low power densities. Very good agreement with measurements of both the radiating and rectifying designs is demonstrated in real office scenarios. Finally the rectenna is connected to a power management unit and the resulting assembly is tested in terms of stored energy while harvesting from a mobile cell-phone call.

A new long-distance microwave reading system is introduced, that we shall call RID (Remotely Identify and Detect), able to locate and identify objects in harsh indoor environments. This is obtained by augmenting standard RFID reader operations with the mono-pulse RADAR principle and electronic beam scanning capabilities. In this way reading failures due to operation in severe fading environments are effectively overcome. The technique is experimented at 2.45 GHz and may be frequency-scalable: the higher the operating frequency the closer can be the tags to be detected. The system is realized by a suitable combination of custom designed components, such as a double printed-monopole array with electronic scanning capability, and of low-power commercial transceivers and MCUs. This results in an handheld low cost device with total dimensions comparable with typical PDAs. The system capabilities are demonstrated in indoor scenarios locating and selecting closely-spaced tagged items, fixed or moving. From this view point RID could be an answer to the intense research and industrial interest solicited by the needs of interacting with systems of devices, such as sensors and actuators, capable of improving the living conditions both at home and in a work space.

The first laparoscopic cholecystectomy in the Department of Surgery of the S. Giacomo Hospital in Rome was performed in April 1991. At that time, for the complete study of the patient and recovery from the operation, a mean period of five days was necessary. Our consolidated experience in laparoscopic cholecystectomy now allows us to perform the operation in the one-day surgery setting.

Gallstone disease is one of the most common health problems world-wide. It is also one of the main causes of medical expenditure in Western countries. Asymptomatic gallstones are defined as stones that have not given rise to biliary cholic or other biliary symptoms. A number of epidemiological cross-sectional screening studies have shown that as many as 66 to 77% of patients with gallstones are asymptomatic. Opinion regarding the development of the disease in the asymptomatic patients has changed in the course of time. In 1992 Friedman, in his review of literature, established that only 1-2% of asymptomatic patients developed severe symptoms or complications early, with fewer complications developing in later years than in the years soon after discovery of the gallstones. Recent prospective epidemiological studies have established that no particular factor has any effect on the natural course of the disease. Laparoscopic cholecystectomy is the gold standard for symptomatic gallstones, but the management of patients with asymptomatic stones remains controversial. This problem is related to the incidence of biliary lesions which has remained substantially unchanged over the past few years. It has recently been demonstrated that the risk of iatrogenic lesions is not entirely dependent upon the surgeon's experience. There is a substantial consensus of agreement that surgical treatment has an unfavourable cost:benefit ratio in asymptomatic patients. The Authors conclude that, because of the condition's benign natural history, a wait-and-see policy is to be recommended in all asymptomatic patients, except for only a few selected cases.