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Topic Review
Different Anisotropic-Strata Interface and Refraction
The strata model inside the earth is close to physical reality. The strata layers can be macro-anisotropic but transversely isotropic, where some are vertically symmetric and the others are not. The macroscopic anisotropy is significant for seismic waves with long wave-length regarding propagation, reflection, refraction, and polarization. This topic review provides the most recent theoretical development related to geophysical applications. 
  • 1.7K
  • 03 Nov 2020
Topic Review
Anomalous Refraction from Anisotropy Media
The transversely isotropic media with a vertical axis of symmetry (VTI media) has been the most popular model for the sedimentary rocks in the interior of the earth. These rocks are usually isotropic within a given layer but strongly anisotropic from layer to layer. Reflection and refraction of acoustic waves between the adjacent rock layers have profound implications in geophysical applications. We discuss some anomalous reflection phenomena of the acoustic wave at the interface between the layered anisotropic rock media. 
  • 1.7K
  • 03 Nov 2020
Topic Review
Lipid Bilayers on Silicon Substrates
Artificial membranes are models for biological systems that are important for several applications. In the present entry we talk about artificial membranes such as supported lipid bilayers (SLB) and ways to self- assemble them. We mainly focus on the results of a new dry evaporation process in high vacuum, i.e., physical vapor deposition, to make samples of dipalmitoylphosphatidylcholine (DPPC) on silicon substrates. We have characterized the main phase transitions and adhesion of our SLBs using high-resolution ellipsometry and AFM techniques. The finding of this new SLB fabrication approach is relevant for the understanding the interaction of lipid bilayers in contact with surfaces in dry environments, with the aim to develop new kinds of lab-on-chip bionanosensors. This discovery is especially relevant in the context of the viability of organisms covered with lipid bilayer structures. An example of this kind of interaction occurs between bilayer-protected viruses, e.g., corona viruses, and solid surfaces, allowing the virus to stay active during long periods of time. The prolonged stability of SLBs on dry SiO2/Si substrates detected in our research can explain the long-term stability of some viruses deposited or adsorbed on dry surfaces, including the SARS-CoV-2 virus. 
  • 1.1K
  • 03 Nov 2020
Topic Review
Nuclear Magnetic Resonance Spectroscopy
A description of standard NMR experiments along with some examples.
  • 2.7K
  • 03 Nov 2020
Topic Review
Polarization Conversion from Anisotropy Media
Anisotropy of the transmission media exerts a strong influence on the reflection and transmission coefficients. Anomalous refraction yields the consequence of polarization conversion for the refracted wave. We discuss this important physical phenomenon by invoking practical interfaces between strongly anisotropic rocks, e.g., between O-shale and A-shale.  
  • 1.3K
  • 02 Nov 2020
Topic Review
The BIANCA Biophysical Model
Cancer ion therapy is constantly growing, thanks to its increased precision and, for heavy ions, its increased biological effectiveness (RBE) with respect to conventional photon therapy. The complex dependence of RBE on many factors demands for biophysical modelling. Up to now only the Local Effect Model (LEM), the Microdosimetric Kinetic Model (MKM) and the “mixed-beam” model are used in clinics. In this work the BIANCA biophysical model, after extensive benchmarking in vitro, was applied to develop a database predicting cell survival for different ions, energies and doses. Following interface with the FLUKA Monte Carlo transport code, for the first time BIANCA was benchmarked against in vivo data obtained by C-ion or proton irradiation of the rat spinal cord. The latter is a well-established model for CNS (Central Nervous System) late effects, which in turn are the main dose-limiting factor for head-and-neck tumors. Furthermore, these data have been considered to validate the LEM version applied in clinics. Although further benchmarking is desirable, the agreement between simulations and data suggests that BIANCA can predict RBE for C-ion or proton treatment of head-and-neck tumors. In particular, the agreement with proton data may be relevant if the current assumption of a constant proton RBE of 1.1 is revised. This work provides the bases for future benchmarking against patient data, as well as the development of other databases for specific tumor types and/or normal tissues.
  • 859
  • 02 Nov 2020
Topic Review
Wearable Airbags
Fall-related injury is a common cause of mortality among the elderly. Hip fractures are especially dangerous and can even be fatal. In this study, a threshold-based preimpact fall detection algorithm was developed for wearable airbags that minimize the impact of falls on the user’s body. Acceleration sum vector magnitude (SVM), angular velocity SVM, and vertical angle, calculated using inertial data captured from an inertial measurement unit were used to develop the algorithm. To calculate the vertical angle accurately, a complementary filter with a proportional integral controller was used to minimize integration errors and the effect of external impacts. In total, 30 healthy young men were recruited to simulate 6 types of falls and 14 activities of daily life. The developed algorithm achieved 100% sensitivity, 97.54% specificity, 98.33% accuracy, and an average lead time (i.e., the time between the fall detection and the collision) of 280.25 ± 10.29 ms with our experimental data, whereas it achieved 96.1% sensitivity, 90.5% specificity, and 92.4% accuracy with the SisFall public dataset. This paper demonstrates that the algorithm achieved a high accuracy using our experimental data, which included some highly dynamic motions that had not been tested previously.
  • 1.2K
  • 01 Nov 2020
Topic Review
Fully Integrated Photoacoustic NO2 Sensor
A fully integrated photoacoustic nitrogen dioxide (NO2) sensor is developed and demonstrated. In this sensor, an embedded photoacoustic cell was manufactured by using an up-to-date 3D printing technique. A blue laser diode was used as a light source for excitation of photoacoustic wave in the photoacoustic cell. The photoacoustic wave is detected by a sensitive microelectromechanical system (MEMS) microphone. Homemade circuits are integrated into the sensor for laser diode driving and signal processing. The sensor was calibrated by using a chemiluminescence NO–NO2–NOX gas analyzer. And the performance of this sensor was evaluated. The linear relationship between photoacoustic signals and NO2 concentrations was verified in a range of below 202 ppb. The limit of detection was determined to 0.86 ppb with an integration time of 1 s. The corresponding normalized noise equivalent absorption was 2.0 × 10−8 cm−1∙W∙Hz−1/2. The stability and the optimal integration time were evaluated with an Allan deviation analysis, from which a detection limit of 0.25 ppb at the optimal integration time of 240 s was obtained. The sensor was used to measure outdoor air and the results agree with that obtained from the NO–NO2–NOX gas analyzer. The low-cost and portable photoacoustic NO2 sensor has a potential application for atmospheric NO2 monitoring.
  • 1.0K
  • 01 Nov 2020
Topic Review
Lower Limb Joint Kinematics
The use of inertial measurement units (IMUs) has gained popularity for the estimation of lower limb kinematics. However, implementations in clinical practice are still lacking. This review shows that methods for lower limb joint kinematics are inherently application dependent. Sensor restrictions are generally compensated with biomechanically inspired assumptions and prior information. Awareness of the possible adaptations in the IMU-based kinematic estimates by incorporating such prior information and assumptions is necessary, before drawing clinical decisions. Future research should focus on alternative validation methods, subject-specific IMU-based biomechanical joint models and disturbed movement patterns in real-world settings.
  • 1.1K
  • 01 Nov 2020
Topic Review
Terahertz Technology
The unique features of terahertz radiation in the context of industrial applications are highlighted. The most common terahertz systems and the way they have been applied in the industry are described. The main barriers from wide spread industry adoption and the outlook of terahertz technology are also discussed.
  • 1.1K
  • 01 Nov 2020
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