Effect of insertion depth on helical antenna performance in a muscle-equivalent phantom

Objectives: To retrospectively investigate the reliability of the age-based formula, year/4 + 3.5 mm in predicting size and year/2 + 12 cm in predicting insertion depth of preformed endotracheal tubes in children and correlate these data with the body mass index. Patients and Methods: Patients were classified into 4 groups according to their nutritional status: thinness, normal weight, overweight, and obesity; we then retrospectively compared the actual size of endotracheal tube and insertion depth to the predicting age-based formula and to the respective bend-to-tip distance of the used preformed tubes. Results: Altogether, 300 patients were included. The actual endotracheal tube size corresponded with the Motoyama formula (64.7%, 90% CI: 60.0-69.1), except for thin patients, where the calculated size was too large (0.5 mm). The insertion depth could be predicted within the range of the bend-to-tip distance and age-based formula in 85.0% (90% CI: 81.3-88.0) of patients. Conclusion: Prediction of the size of cuffed preformed endotracheal tubes using the formula of Motoyama was accurate in most patients, except in thin patients (body mass index < −2 SD). The insertion depth of the tubes was mostly in the range of the age-based-formula to the bend-to-tip distance.

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Enhancement in Dual Polarization Phased Array Antenna Performance and Calibration Techniques for Weather Radar Applications

2020 International Symposium on Antennas & Propagation (APSYM) ◽

10.1109/apsym50265.2020.9350708 ◽

2020 ◽

Author(s):

Steffy Benny ◽

Swaroop Sahoo

Keyword(s):

Phased Array ◽

Weather Radar ◽

Array Antenna ◽

Dual Polarization ◽

Phased Array Antenna ◽

Antenna Performance ◽

Radar Applications ◽

Calibration Techniques

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Photoconductive Antennas: Effects of Crystallographic Orientation of GaAs Substrate and the Period of Plasmon Grid on THz Antenna Performance (Ann. Phys. 8/2021)

Annalen der Physik ◽

10.1002/andp.202170025 ◽

2021 ◽

Vol 533 (8) ◽

pp. 2170025

Author(s):

Arseniy M. Buryakov ◽

Maxim S. Ivanov ◽

Dinar I. Khusyainov ◽

Anastasia V. Gorbatova ◽

Vladislav R. Bilyk ◽

...

Keyword(s):

Crystallographic Orientation ◽

Gaas Substrate ◽

Photoconductive Antennas ◽

Antenna Performance ◽

Thz Antenna

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Interactions of Linear Analogues of Battacin with Negatively Charged Lipid Membranes

Membranes ◽

10.3390/membranes11030192 ◽

2021 ◽

Vol 11 (3) ◽

pp. 192

Author(s):

Kinga Burdach ◽

Dagmara Tymecka ◽

Aneta Urban ◽

Robert Lasek ◽

Dariusz Bartosik ◽

...

Keyword(s):

Lipid Membranes ◽

Liquid Crystalline ◽

Lipid Membrane ◽

Attenuated Total Reflection ◽

Gram Positive ◽

Insertion Depth ◽

Force Microscopy ◽

Acyl Chains ◽

Hydrophobic Portion ◽

Membrane Fluidization

The increasing resistance of bacteria to available antibiotics has stimulated the search for new antimicrobial compounds with less specific mechanisms of action. These include the ability to disrupt the structure of the cell membrane, which in turn leads to its damage. In this context, amphiphilic lipopeptides belong to the class of the compounds which may fulfill this requirement. In this paper, we describe two linear analogues of battacin with modified acyl chains to tune the balance between the hydrophilic and hydrophobic portion of lipopeptides. We demonstrate that both compounds display antimicrobial activity with the lowest values of minimum inhibitory concentrations found for Gram-positive pathogens. Therefore, their mechanism of action was evaluated on a molecular level using model lipid films mimicking the membrane of Gram-positive bacteria. The surface pressure measurements revealed that both lipopeptides show ability to bind and incorporate into the lipid monolayers, resulting in decreased ordering of lipids and membrane fluidization. Atomic force microscopy (AFM) imaging demonstrated that the exposure of the model bilayers to lipopeptides leads to a transition from the ordered gel phase to disordered liquid crystalline phase. This observation was confirmed by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) results, which revealed that lipopeptide action causes a substantial increase in the average tilt angle of lipid acyl chains with respect to the surface normal to compensate for lipopeptide insertion into the membrane. Moreover, the peptide moieties in both molecules do not adopt any well-defined secondary structure upon binding with the lipid membrane. It was also observed that a small difference in the structure of a lipophilic chain, altering the balance between hydrophobic and hydrophilic portion of the molecules, results in different insertion depth of the active compounds.

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