Redox-Switching in a Viologen-type Adlayer: An Electrochemical Shell-Isolated Nanoparticle Enhanced Raman Spectroscopy Study on Au(111)-(1 x 1) Single Crystal Electrodes

We reported the first application of in situ shell-isolated nanoparticle enhanced Raman spectroscopy (SHINERS) to an interfacial redox reaction under electrochemical conditions. We construct gap-mode sandwich structures composed of a thiol-terminated HS-6V6H viologen adlayer immobilized on a single crystal Au(111)-(1x1) electrode and covered by Au(60 nm)@SlO(2) core shell nanoparticles acting as plasmonic antennas. We observed high-quality, potential-dependent Raman spectra of the three viologen species V(2+),V(+center dot) and V(0) on a well-defined Au(111) substrate surface and could map their potential-dependent evolution. Comparison with experiments on powder samples revealed an enhancement factor of the nonresonant Raman modes of similar to 3 x 10(5), and up to 9 x 10(7) for the resonance modes. The study illustrates the unique capability of SHINERS and its potential in the entire field of electrochemical surface science to explore structures and reaction pathways on well-defined substrate surfaces, such as single crystals, for molecular, (electro-)- catalytic, bioelectrochemical systems up to fundamental double layer studies at electrified solid/liquid interfaces.

A twin spiral planar antenna for UWB medical radars

A planar-spiral antenna to be used in an ultrawideband (UWB) radar system for heart activity monitoring is presented. The antenna, named “twin,” is constituted by two spiral dipoles in a compact structure. The reflection coefficient at the feed point of the dipoles is lower than −8 dB over the 3–12 GHz band, while the two-dipoles coupling is about −20 dB. The radiated beam is perpendicular to the plane of the spiral, so the antenna is wearable and it may be an optimal radiator for a medical UWB radar for heart rate detection. The designed antenna has been also used to check some hypotheses about the UWB radar heart activity detection mechanism. The radiation impedance variation, caused by the thorax vibrations associated with heart activity, seems to be the most likely explanation of the UWB radar operation.

Antenna Simulations and Measurements of Focal Plane Array Facet Reflectors

We present a conceptual prototype model of a focal plane array unit for the STEAMR instrument, highlighting the challenges presented by the required high relative beam proximity of the instrument and focus on how edge-diffraction effects contribute to the array's performance. The analysis was carried out as a comparative process using both PO & PTD and MoM techniques. We first highlight general differences between these computational techniques, with the discussion focusing on diffractive edge effects for near-field imaging reflectors with high truncation. We then present the results of in-depth modeling analyses of the STEAMR focal plane array followed by near-field antenna measurements of a breadboard model of the array. The results of these near-field measurements agree well with both simulation techniques although MoM shows slightly higher complex beam coupling to the measurements than PO & PTD.

Low Mass Calibration Target for MM-Wave Remote Sensing Instruments

The reliability of millimeter and sub-millimeter wave radiometer measurements is dependent on the accuracy of the loads they employ as calibration targets. In the recent past on-board calibration loads have been developed for a variety of satellite remote sensing instruments. Unfortunately some of these have suffered from calibration inaccuracies which had poor thermal performance of the calibration target as the root cause. Stringent performance parameters of the calibration target such as low reflectivity, high temperature uniformity, low mass and low power consumption combined with low volumetric requirements remain a challenge for the space instrument developer. In this paper we present a novel multi-layer absorber concept for a calibration load which offers an excellent compromise between very good radiometric performance and temperature uniformity and the mass and volumetric constraints required by space-borne calibration targets.

Influence of inspiration to expiration ratio on cyclic recruitment and derecruitment of atelectasis in a saline lavage model of acute respiratory distress syndrome*

OBJECTIVE Cyclic recruitment and derecruitment of atelectasis can occur during mechanical ventilation, especially in injured lungs. Experimentally, cyclic recruitment and derecruitment can be quantified by respiration-dependent changes in PaO2 (ΔPaO2), reflecting the varying intrapulmonary shunt fraction within the respiratory cycle. This study investigated the effect of inspiration to expiration ratio upon ΔPaO2 and Horowitz index. DESIGN Prospective randomized study. SETTING Laboratory investigation. SUBJECTS Piglets, average weight 30 ± 2 kg. INTERVENTIONS At respiratory rate 6 breaths/min, end-inspiratory pressure (Pendinsp) 40 cm H2O, positive end-expiratory pressure 5 cm H2O, and FIO2 1.0, measurements were performed at randomly set inspiration to expiration ratios during baseline healthy and mild surfactant depletion injury. Lung damage was titrated by repetitive surfactant washout to induce maximal cyclic recruitment and derecruitment as measured by multifrequency phase fluorimetry. Regional ventilation distribution was evaluated by electrical impedance tomography. Step changes in airway pressure from 5 to 40 cm H2O and vice versa were performed after lavage to calculate PO2-based recruitment and derecruitment time constants (TAU). MEASUREMENTS AND MAIN RESULTS In baseline healthy, cyclic recruitment and derecruitment could not be provoked, whereas in model acute respiratory distress syndrome, the highest ΔPaO2 were routinely detected at an inspiration to expiration ratio of 1:4 (range, 52-277 torr [6.9-36.9 kPa]). Shorter expiration time reduced cyclic recruitment and derecruitment significantly (158 ± 85 torr [21.1 ± 11.3 kPa] [inspiration to expiration ratio, 1:4]; 25 ± 12 torr [3.3 ± 1.6 kPa] [inspiration to expiration ratio, 4:1]; p < 0.0001), whereas the PaO2/FIO2 ratio increased (267 ± 50 [inspiration to expiration ratio, 1:4]; 424 ± 53 [inspiration to expiration ratio, 4:1]; p < 0.0001). Correspondingly, regional ventilation redistributed toward dependent lung regions (p < 0.0001). Recruitment was much faster (TAU: fast 1.6 s [78%]; slow 9.2 s) than derecruitment (TAU: fast 3.1 s [87%]; slow 17.7 s) (p = 0.0078). CONCLUSIONS Inverse ratio ventilation minimizes cyclic recruitment and derecruitment of atelectasis in an experimental model of surfactant-depleted pigs. Time constants for recruitment and derecruitment, and regional ventilation distribution, reflect these findings and highlight the time dependency of cyclic recruitment and derecruitment.

Use of outdoor ranges by laying hens in different sized flocks.

In studies assessing outdoor range use of laying hens, the number of hens seen on outdoor ranges is inversely correlated to flock size. The aim of this study was to assess individual ranging behavior on a covered (veranda) and an uncovered outdoor run (free-range) in laying hen flocks varying in size. Five to ten percent of hens (aged 9–15 months) within 4 small (2–2500 hens), 4 medium (5–6000), and 4 large (≥9000) commercial flocks were fitted with radio frequency identification (RFID) tags. Antennas were placed at both sides of all popholes between the house and the veranda and the veranda and the free-range. Ranging behavior was directly monitored for approximately three weeks in combination with hourly photographs of the free-range for the distribution of hens and 6h long video recordings on two parts of the free-range during two days. Between 79 and 99% of the tagged hens were registered on the veranda at least once and between 47 and 90% were registered on the free-range at least once. There was no association between the percentage of hens registered outside the house (veranda or free-range) and flock size. However, individual hens in small and medium sized flocks visited the areas outside the house more frequently and spent more time there than hens from large flocks. Foraging behavior on the free-range was shown more frequently and for a longer duration by hens from small and medium sized flocks than by hens from large flocks. This difference in ranging behavior could account for the negative relationship between flock size and the number of hens seen outside at one point of time. In conclusion, our work describes individual birds’ use of areas outside the house within large scale commercial egg production.

Doppler Orbit Determination of Deep Space Probes by the Bernese GNSS Software: First Results of the Combined Orbit Determination from DSN and Inter-Satellite Ka-Band Data from the Grail Mission

Navigation of deep space probes is most commonly operated using the spacecraft Doppler tracking technique. Orbital parameters are determined from a series of repeated measurements of the frequency shift of a microwave carrier over a given integration time. Currently, both ESA and NASA operate antennas at several sites around the world to ensure the tracking of deep space probes. Just a small number of software packages are nowadays used to process Doppler observations. The Astronomical Institute of the University of Bern (AIUB) has recently started the development of Doppler data processing capabilities within the Bernese GNSS Software. This software has been extensively used for Precise Orbit Determination of Earth orbiting satellites using GPS data collected by on-board receivers and for subsequent determination of the Earth gravity field. In this paper, we present the currently achieved status of the Doppler data modeling and orbit determination capabilities in the Bernese GNSS Software using GRAIL data. In particular we will focus on the implemented orbit determination procedure used for the combined analysis of Doppler and intersatellite Ka-band data. We show that even at this earlier stage of the development we can achieve an accuracy of few mHz on two-way S-band Doppler observation and of 2 µm/s on KBRR data from the GRAIL primary mission phase.