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Microwave-induced thermoacoustic (TA) imaging is efficient in detecting anomalous absorption areas, especially breast tumors. The operation of previous imaging systems has generally suffered from complexity, and early-stage tumors could be missed because of signal loss. In this paper, we report a variable-curvature and multi-dimensional screening method realized by combining a redesigned adaptive algorithm and an integrated TA breast screening system (ITBCS) comprising a flexible detector and a traction device designed for multi-axis rotation. In contrast to conventional TA imaging systems, the proposed system improves the ability to identify early-stage breast tumors, with a simplified system and operational process. Variable curvature is achieved by the flexible characteristics of the detector, which achieves good shape adaptation between the tissue and the detector. Moreover, multi-dimensional scanning is achieved by the multi-axis traction device and meets the requirements for angle transformation and dynamic imaging. The experimental results indicate that ITBCS exhibits a good performance in detecting breast tumors. Faster screening makes inspection more efficient, thereby improving clinical applicability and providing a convenient facility for large-scale physical examination. [ABSTRACT FROM AUTHOR]

The objectives of this study were to assess the microbial quality of honey, evaluate the effect of microwaves on microbial survival, and assess the antibacterial activity of honey. Bacteria, yeast and mold were evaluated in samples before and after microwave treatment. Dominant bacterial contaminants were also identified. The antibacterial activity of honey was assessed against nine pathogens using an agar well diffusion assay. The minimum inhibitory concentration was determined for four honey samples that exhibited the highest antibacterial activity. In addition, one sample of Manuka honey was tested to compare its microbial load as well as its antibacterial activity to local honey samples. Sequencing using 16S rRNA gene was used for the identification of dominant bacteria. The average standard plate count, yeasts and molds were 286.5, 161.0 and 25.5 CFU/g, respectively. Microwave treatment decreased microbial populations gradually with increasing power levels and exposure times. The present study indicated that raw honey had a significant antibacterial activity which decreased following microwave treatment. The identity of 125 isolates was confirmed with Bacillus being most frequently isolated. [ABSTRACT FROM AUTHOR]

A method for contact-free determination of the sheet resistance of large-area and arbitrary shaped wafers or sheets coated with graphene and other (semi) conducting ultrathin layers is described, which is based on an open dielectric loaded microwave cavity. The sample under test is exposed to the evanescent resonant field outside the cavity. A comparison with a closed cavity configuration revealed that radiation losses have no significant influence of the experimental results. Moreover, the microwave sheet resistance results show good agreement with the dc conductivity determined by four-probe van der Pauw measurements on a set of CVD samples transferred on quartz. As an example of a practical application, correlations between the sheet resistance and deposition conditions for CVD graphene transferred on quartz wafers are described. Our method has a high potential as measurement standard for contact-free sheet resistance measurement and mapping of large area graphene samples. [ABSTRACT FROM AUTHOR]

Environmentally-friendly microwave heating is increasingly used in polymer chemistry and technology. The selectivity and highly efficiency in the heat transfer present a huge advantage in systems based on recycling, improving their productivity and economic competitiveness. In case of the industrial recycling of waste rubbers, especially end-of-life tires, microwave-induced devulcanization and pyrolysis are nowadays considered as promising approaches. This work aims to report the recent progress in microwave treatments of vulcanized rubbers with different compositions. Special attention is focused on the correlation between microwave processing parameters and devulcanization/pyrolysis efficiency, which have a significant impact on the structure-property relationships of the obtained products. Moreover, the main challenges affecting the future of the industrial application of the microwave technology in rubber recycling are also discussed. [ABSTRACT FROM AUTHOR]

The article presents a study aimed to leverage passive microwave (PM) data from the special microwave imager (SSMI) from raw swath data across High Mountain Asia (HMA) from October 1987 to October 2009. The study is undertaken through the measurement of temperature across 10 catchments for 8,340 days. The results of the study show that the average winter (December-January-February, DJF) SWE ranges from zero up to more than 140 mm in some high-elevation areas.

Microwave and ultrasound have been demonstrated to be outstanding process intensification techniques for transesterification of oil. According to their mechanisms, simultaneous effects can surely bring about better enhancement than sole microwave or ultrasound. Therefore, this study aimed to investigate the important factors and their suitable levels in the KOH-catalyzed transesterification of soybean oil with methanol by using synergistic assistance of microwave-ultrasound (CAMU). The feasibility of application of CAMU in transesterification of oil was demonstrated. When the dosage of methanol, soybean oil and KOH were 15.4 g, 34.7 g (with methanol-to-oil molar ratio of 12:1) and 1 g, respectively, and the microwave power, ultrasonic power, ultrasonic mode, reaction temperature and reaction time were 700 W, 800 W, 1:0, 65 °C and 6 min, respectively, the transesterification reached 98.0% of yield, being the highest yield among all the results obtained; while by using 600 W of microwave plus stirring instead of CAMU, only 57.4% of yield could be obtained. Compared with other reaction techniques, the transesterification by applying novel CAMU was found to have remarkable advantages. Furthermore, by monitoring the variation of real-time temperature and microwave power during transesterification reactions with different microwave operation time and by taking comparison of the corresponding yield, it was demonstrated that the main reason for the acceleration of microwave-assisted transesterification was the polarization and further activation of reactants caused by microwave irradiation, but not the factor of fast heating. [ABSTRACT FROM AUTHOR]

Stroke patients should be dispatched at the highest level of care available in the shortest time. In this context, a transportable system in specialized ambulances, able to evaluate the presence of an acute brain lesion in a short time interval (i.e., few minutes), could shorten delay of treatment. UWB radar imaging is an emerging diagnostic branch that has great potential for the implementation of a transportable and low-cost device. Transportability, low cost and short response time pose challenges to the signal processing algorithms of the backscattered signals as they should guarantee good performance with a reasonably low number of antennas and low computational complexity, tightly related to the response time of the device. The paper shows that a PCA-based preprocessing algorithm can: (1) achieve good performance already with a computationally simple beamforming algorithm; (2) outperform state-of-the-art preprocessing algorithms; (3) enable a further improvement in the performance (and/or decrease in the number of antennas) by using a multistatic approach with just a modest increase in computational complexity. This is an important result toward the implementation of such a diagnostic device that could play an important role in emergency scenario. [ABSTRACT FROM AUTHOR]

Analysis of recent publications on microwave probe diagnostics shows that some assumptions used in microwave probe models are unrealistic and ambiguous, which puts into question the validity of those diagnostics. [ABSTRACT FROM AUTHOR]

We report the design of a real-time thermoacoustic (TA) scanner dedicated to imaging deep breast tumors and investigate its imaging performance. The TA imaging system is composed of an ultrashort microwave pulse generator and a ring transducer array with 384 elements. By vertically scanning the transducer array that encircles the breast phantom, we achieve real-time, 3D thermoacoustic imaging (TAI) with an imaging speed of 16.7 frames per second. The stability of the microwave energy and its distribution in the cling-skin acoustic coupling cup are measured. The results indicate that there is a nearly uniform electromagnetic field in each XY-imaging plane. Three plastic tubes filled with salt water are imaged dynamically to evaluate the real-time performance of our system, followed by 3D imaging of an excised breast tumor embedded in a breast phantom. Finally, to demonstrate the potential for clinical applications, the excised breast of a ewe embedded with an ex vivo human breast tumor is imaged clearly with a contrast of about 1:2.8. The high imaging speed, large field of view, and 3D imaging performance of our dedicated TAI system provide the potential for clinical routine breast screening. [ABSTRACT FROM PUBLISHER]

A technology-independent, inherently nonlinear approach is proposed for the compact modelling of high-frequency noise in microwave transistors under large-signal operating conditions. For the compact nonlinear noise model formulation we assume that noise generation can be described by a suitable set of distributed stochastic processes perturbing a very general, non-quasi-static deterministic description of the electron device, in accordance with the strategies adopted in physics-based methods for the choice and exploitation of microscopic diffusion noise sources. The propagation of the internal distributed noise sources up to the intrinsic device terminals leads to a set of non-stationary, correlated equivalent noise generators, nonlinearly controlled by the instantaneous large-signal working point of the device. Starting from a first formulation for the generators, formally derived from a physics-based description of the noise generation mechanisms widely adopted in distributed numerical modeling, mild approximations provide a fully behavioral representation that can be empirically extracted on the basis of measurement data only, and can be easily implemented into commercial computer-aided design tools by means of conventional, uncorrelated noise sources. As far as small-signal (i.e., linear) bias-dependent operation is concerned, it is shown how well-known, widely applied compact models for high-frequency noise can be considered as linearized special cases of the proposed approach. For a full validation, experimental examples are provided, both in small- and large-signal operation, for a GaAs-pHEMT, by considering the case study of a broad-band low-noise amplifier progressively driven into nonlinear regime by an increasing power interferer. [ABSTRACT FROM AUTHOR]

We present vM21 MIPAS temperatures from the lower stratosphere to the lower thermosphere, which cover all optimized resolution measurements performed by MIPAS in the Middle Atmosphere, Upper Atmosphere and NoctiLucent Cloud modes during its lifetime. i.e., from January 2005 to March 2012. The main upgrades with respect to the previous version of MIPAS temperatures (vM11) are the update of the spectroscopic database, the use of a different climatology of atomic oxygen and carbon dioxide, and the improvement of important technical aspects of the retrieval setup (temperature gradient along the line of sight and offset regularizations, apodization accuracy). Addition ally, an updated version of ESA calibrated L1b spectra (5.02/5.06) is used. The vM21 temperatures correct the main systematic errors of the previous version because they on average provide a 1-2 K warmer stratopause and middle mesosphere, and a 6-10 K colder mesopause (except in high latitude summers) and lower thermosphere. These lead to a remarkable improvement of MIPAS comparisons with ACE-FTS, MLS, OSIRIS, SABER, SOFIE and the two Rayleigh lidars at Mauna Loa and Table Mountain, that, with few specific exceptions, typically exhibit differences smaller than 1 K below 50km and than 2 K at 50-80 km in spring, autumn, winter at all latitudes, and summer at low to mid-latitudes. Differences in the high latitude summers are typically smaller than 1 K below 50 km, smaller than 2K at 50-65 km and 5 K at 65-80 km. Differences with the other instruments in the mid-mesosphere are generally negative. MIPAS mesopause is within 4 K of the other instruments measurements, except in the high latitude summers, where it is within 5-10K of the other instruments, being warmer than SABER, MLS and OSIRIS and colder than ACE-FTS and SOFIE. The agreement in the lower thermosphere is typically better than 5 K, except for high latitudes during 25 spring and summer, where MIPAS usually exhibits larger vertical gradients [ABSTRACT FROM AUTHOR]

We demonstrate dynamic stabilization of a strongly interacting quantum spin system realized in a spin-i atomic Bose-Einstein condensate. The spinor Bose-Einstein condensate is initialized to an unstable fixed point of the spin-nematic phase space, where subsequent free evolution gives rise to squeezing and quantum spin mixing. To stabilize the system, periodic microwave pulses are applied that rotate the spin- nematic many-body fluctuations and limit their growth. The stability diagram for the range of pulse periods and phase shifts that stabilize the dynamics is measured and compares well with a stability analysis. [ABSTRACT FROM AUTHOR]

The University of Alabama at Huntsville (UAH), Remote Sensing Systems (RSS), and the National Oceanic and Atmospheric Administration (NOAA) have constructed long-term temperature records for deep atmospheric layers using satellite Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU) observations. However, these groups disagree on the magnitude of global temperature trends since 1979, including the trend for the midtropospheric layer (TMT). This study evaluates the selection of the MSU TMT warm target factor for the NOAA-9 satellite using five homogenized radiosonde products as references. The analysis reveals that the UAH TMT product has a positive bias of 0.051 ± 0.031 in the warm target factor that artificially reduces the global TMT trend by 0.042 K decade−1 for 1979-2009. Accounting for this bias increases the global UAH TMT trend from 0.038 to 0.080 K decade−1, effectively eliminating the trend difference between UAH and RSS and decreasing the trend difference between UAH and NOAA by 47%. This warm target factor bias directly affects the UAH lower tropospheric (TLT) product and tropospheric temperature trends derived from a combination of TMT and lower stratospheric (TLS) channels. [ABSTRACT FROM AUTHOR]

Abstract: Piezoelectric c-textured Al(1−x)Sc x N thin films, where the Sc relative concentration, x, varies in the range 0–0.15 have been studied in view of radio frequency (RF) electro-acoustic applications. Thin film bulk acoustic wave resonators (FBARs) employing these films were fabricated and characterized as a function of the Sc concentration for the first time. The measured electromechanical coupling is found to increase by as much as 100% in the above concentration range. The results from this work underline the potential of the c-textured Al(1−x)Sc x N based FBARs for wide band RF applications. [Copyright &y& Elsevier]

In this letter, we present the design and fabrication of a novel ZnO-based film bulk acoustic wave resonator (FBAR) microwave devices. The novel FBAR devices employ a new-type of Bragg reflector with very thin chromium (Cr) layer formed between SiO2 and W films. The Cr layer seems to enhance the adhesion between SiO2 and W layers. The novel FBAR devices show good return losses (S11) and high Q-factors at the frequency range of 2.7-3.0 GHz. This approach will be very helpful for mobile worldwide interoperability for microwave access applications. [ABSTRACT FROM PUBLISHER]