The super-hyper singular integrals in the EFIE of the second form in Eq. (1) were prohibitive and there was no direct way to evaluate them. But we have developed a novel technique to efficiently handle such singularities based on the series representation of the Green's function and a constant current approximation. The approach allows us to solve the EFIE of the second form directly. It has locality in its unknown association with space, and hence is easy to incorporate with FMA. The derived closed-form formulas can be used to calculate both selfinteraction and near-interaction terms in the impedance matrix very accurately and conveniently. The numerical errors in the scheme mainly come from the lower-order approximation for current and geometry. We can easily implement the higherorder approximation of current in the scheme because the introduction of higher-order terms only weakens the degree of singularity. We will incorporate the higher-order representation of geometry for the scheme in the future and improve the overall accuracy further. ABSTRACT: A method of measurement of the real and imaginary parts of high dielectric constant materials at THz frequencies is described. The method is based on application of double-layer sample with variable distance between slabs. The recorded power transmittance inerferogram is employed for reconstructing complex permittivity of a material under test. Reconstructing algorithm and its realization are presented. Example of measurements of the alumina sample in 0.8 -1.1 THz has demonstrated a good agreement with independent data obtained from the time-domain terahertz spectroscopy method. ABSTRACT: Negative-permeability sub-wavelength particles, namely split-ring resonators and spiral resonators, are compared and their performances analyzed for a different number of concentric rings and spiral turns, respectively. Left-handed lines are designed, fabricated, and measured that use multiple complementary split-ring and spiral resonators. More compact structures are obtained, with improved characteristics.
The global spread of bacterial resistance to antibiotics promotes a search for alternative approaches to eradication of pathogenic bacteria. One alternative is using photosensitizers for inhibition of Gram-positive and Gram-negative bacteria under illumination. Due to low penetration of visible light into tissues, applications of photosensitizers are currently limited to treatment of superficial local infections. Excitation of photosensitizers in the dark can be applied to overcome this problem. In the present work, dark antibacterial activity of the photosensitizer Rose Bengal alone and in combination with antibiotics was studied. The minimum inhibitory concentrations (MIC) value of Rose Bengal against S. aureus dropped in the presence of sub-MIC concentrations of ciprofloxacin, levofloxacin, methicillin, and gentamicin. Free Rose Bengal at sub-MIC concentrations can be excited in the dark by ultrasound at 38 kHz. Rose Bengal immobilized onto silicon showed good antibacterial activity in the dark under ultrasonic activation, probably because of Rose Bengal leaching from the polymer during the treatment. Exposure of bacteria to Rose Bengal in the dark under irradiation by electromagnetic radio frequency waves in the 9 to 12 GHz range caused a decrease in the bacterial concentration, presumably due to resonant absorption of electromagnetic energy, its transformation into heat and subsequent excitation of Rose Bengal.
A single-pixel imaging remote sensor operating at 330 GHz is described. It is based on a frequency modulated continuous wave (FMCW) and aimed at detection of concealed objects for ranges up to 40 m. The system consists of 2 horn-lens antennas integrated with a homodyne transceiver. The synthesized linear FMCW signal at X-band is multiplied by a factor of 32 to generate the transmitted signal. An intermediate frequency (IF) signal obtained in the output port of the 2-nd harmonic mixer is employed for image processing. Distance measurements were made by performing data acquisition unit based on LabView interface and resulting in a range resolution about 1 cm. Examples of 2D and 3D images reconstructed with this sensor are presented.
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