Design of a Compact and Minimalistic Intermediate Phase Shifting Feed Network for Ka-Band Electrical Beam Steering.

Intermediate phase shifting is a footprint- and cost-reduction technique for reconfigurable feed networks. These feed networks are utilized in antenna arrays to perform electrical beam steering. In intermediate phase shifting, a phase shifter is shared between two adjacent antennas. Conventionally, antennas only have individual phase shifters. With shared phase shifters, we reduce the number of components and the footprint by 25%. Consequently, this decreases the price and enables designs at millimeter-wave frequencies where space is limited due to frequency-dependent antenna spacing. This intermediate phase shifting is demonstrated by designing a reconfigurable feed network for the Ka-band that generates a continuous phase shift profile for beam steering. Due to the use of varactors and a novel biasing method, it does not require expensive beamformer integrated chips or lumped components for biasing. The feed network is combined with a 4 × 4 antenna array to demonstrate its beam-steering capabilities. The result is a high-density and minimalistic design that fits in a small volume of 25.6 × 25.6 × 0.95 mm3. With this small antenna array, the main beam is steered at ±40∘ broadside, providing full 1D and restricted 2D steering. It is a potential candidate for wireless sensor and mobile networks.

Evaluation of Polydimethylsiloxane (PDMS) as a Substrate for the Realization of Flexible/Wearable Antennas and Sensors.

To demonstrate that the silicone-based polymer polydimethylsiloxane (PDMS) is suitable as a substrate for flexible/wearable antennae and sensors, an investigation of its various properties was carried out. The substrate was first developed in compliance with the requirements, and then its anisotropy was investigated using an experimental bi-resonator approach. This material exhibited modest but discernible anisotropy, with values of ~6.2/25 % for the dielectric constant and loss tangent, respectively. Its anisotropic behavior was confirmed by a parallel dielectric constant (εpar) ~2.717 and an evaluated perpendicular dielectric constant (εperp) ~2.570-εpar > εperp by 5.7%. Temperature affected PDMS's dielectric properties. Lastly, the simultaneous impact of bending and anisotropy of the flexible substrate PDMS on the resonance properties of planar structures was also addressed, and these had diametrically opposed effects. PDMS appears to be a good contender as a substrate for flexible/wearable antennae and sensors based on all experimental evaluations conducted for this research.

A 4 × 4 Active Antenna Array with Adjustable Beam Steering.

An adjustable 4×4 antenna array with electrical beam steering and polarization control is presented. Here, adjustability means the ability to correct the beam steering angle post-calibration. The objective is to improve the steering accuracy which is critical in point-to-point communication as inaccuracy will cause transmission failure due to a missed target. The accuracy is enhanced by adjusting the beam steering angle in beamforming calculations. To execute this, the system is calibrated by measuring several unit cells of a partial 4×4 array structure at different voltage bias points and calculating an average model of the phase shift profile. This reduces the phase error from variations between components and robust beam steering is achieved. This technique is utilized in far-field measurements, and fairly accurate initial beam steering angles are achieved at 3 GHz. The accuracy is further improved by over or under steering the desired angle in the beamforming calculations to finally achieve the steering angle of interest with an accuracy of 2∘. Overall, the main beam is incrementally steered from 0∘ to 45∘ with the gain ranging from 4.7 dB to 2.8 dB. The polarization control is also demonstrated in horizontal and vertical directions for a linearly polarized wave.

Brain Implantable End-Fire Antenna with Enhanced Gain and Bandwidth.

An end-fire radiating implantable antenna with a small footprint and broadband operation at the frequency range of 3-5 GHz is proposed for high-data-rate wireless communication in a brain-machine interface. The proposed Vivaldi antenna was implanted vertically along the height of the skull to avoid deformation in the radiation pattern and to compensate for a gain-loss caused by surrounding lossy brain tissues. It was shown that the vertically implanted end-fire antenna had a 3 dB higher antenna gain than a horizontally implanted broadside radiating antenna discussed in recent literature. Additionally, comb-shaped slot arrays imprinted on the Vivaldi antenna lowered the resonant frequency by approximately 2 GHz and improved the antenna gain by more than 2 dB compared to an ordinary Vivaldi antenna. An antenna prototype was fabricated and then tested for verification inside a seven-layered semi-solid brain phantom where each layer had similar electromagnetic material properties as actual brain tissues. The measured data showed that the antenna radiated toward the end-fire direction with an average gain of -15.7 dBi under the frequency of interest, 3-5 GHz. A link budget analysis shows that reliable wireless communication can be achieved over a distance of 10.8 cm despite the electromagnetically harsh environment.

Oral absorption of voriconazole is affected by SLCO2B1 c.*396T>C genetic polymorphism in CYP2C19 poor metabolizers.

High pharmacokinetic variability of voriconazole is mainly explained by CYP2C19 phenotype, but there are still unknown factors affecting the variability. In this study, the effect of solute carrier organic anion transporter family member 2B1 (SLCO2B1) genotype on the pharmacokinetics (PKs) of voriconazole was evaluated in 12 healthy CYP2C19 poor metabolizers after a single administration of voriconazole 200 mg intravenously and orally. In addition, the influence of CYP3A4 enzyme activity was also explored. The oral absorption of voriconazole was decreased and delayed in the subjects with the SLCO2B1 c.*396T>C variant compared to the subjects with wild type. However, the CYP3A activity markers measured in this study did not show significant association with metabolism of voriconazole. The results suggest that the SLCO2B1 c.*396T>C may be associated with the decreased function of intestinal OATP2B1, and it could contribute to interindividual PK variability of voriconazole.

Proposal of 28 GHz In Vitro Exposure System Based on Field Uniformity for Three-Dimensional Cell Culture Experiments.

This paper proposes a novel in vitro exposure system operating at millimeter-wave (mmWave) 28 GHz, one of the frequency bands under consideration for fifth generation (5G) communication. We employed the field uniformity concept along cross-sectional observation planes at shorter distances from the radiation antenna for better efficiency and a small-size system. A choke-ring antenna was designed for this purpose in consideration of a wider beamwidth (BW) and a symmetric far-field pattern across three principal planes. The permittivity of Dulbecco's modified Eagle's medium solution was measured to examine the specific absorption rate (SAR) of the skin cell layer inside a Petri dish model for a three-dimensional (3D) cell culture in vitro experiment. The best deployment of Petri dishes, taking into account a geometrical field symmetry, was proposed. Local SAR values within the cell layer among the Petri dishes were determined with different polarization angles. It was determined that this polarization effect should be considered when the actual exposure and deployment were conducted. We finally proposed an in vitro exposure system based on the field uniformity including downward exposure from an antenna for 3D cell culture experiments. A small-size chamber system was obtained, and the size was estimated using the planar near-field chamber design rule. Bioelectromagnetics. 2019;40:445-457. © 2019 Bioelectromagnetics Society.

Anatomical study of the mandibular angle and body in wide mandibular angle cases.

BACKGROUND: Mandibular angle reduction surgery is widely used for aesthetic purposes. Because inferior alveolar nerve injury is a common complication of this surgery, the anatomical location of this nerve must be known before surgery. This study investigated the relative location of the inferior alveolar nerve in mesofacial and brachyfacial groups. METHODS: Panoramic views of patients were divided into Groups A (gonial angle < 120°) and B (gonial angle > 120°). For the analysis, the magnification of each image was standardized and the following parameters were measured: (1) gonial angle; (2) distance from the alveolar ridge at the center of the first and second premolars and first and second molars to (a) the inferior margin of the inferior alveolar canal and (b) the inferior margin of the mandible; (3) distance from the posterior alveolar ridge to the gonial angle and to (a) on the same line; (4) size of the first and second molars. RESULTS: Statistical analysis showed that there were no significant differences (P > 0.05) between Group A and Group B with respect to the distance from the alveolar ridge to the inferior alveolar canal in the first premolar, second premolar, and first molar. The differences between Group A and Group B with respect to the distance from the alveolar ridge to the inferior margin of the mandible for the second premolar, first molar, second molar and gonial angle were 0.7, 1.5, 2.8, and 7.0 mm, respectively (P < 0.05). The differences between Group A and Group B with respect to the distances from the inferior margin of the inferior alveolar canal to the inferior margin of the mandible for the same landmarks were 0.7, 1.1, 1.3, and 5.7 mm, respectively (P < 0.05). CONCLUSION: The difference in length from the alveolar ridge to the mandibular canal between the two groups was minimal, but the length to the gonial angle differed significantly. These results will help reduce inferior alveolar nerve injury during mandibular angle reduction surgery.

The effects of botulinum toxin A on the survival of a random cutaneous flap.

BACKGROUND: Although interest in flap surgery has increased, a satisfactory research study on supportive drugs or methods for flap surgery has not been seen in the literature thus far. Despite several studies using botulinum toxin A for flap surgery being reported, their efforts to clarify the mechanisms are not sufficient. Therefore, the authors have studied the effect of botulinum toxin A on random cutaneous flap survival in a rat model under the hypothesis that it affects the microvascular system. METHOD: Thirty 10-week-old Sprague-Dawley rats were divided into experimental (n=15) and control groups (n=15). The experimental group used 1.5 IU (International Units) of botulinum toxin A, and the control group used normal saline. A 2x8 cm random cutaneous flap was designed on the rats and then elevated. Normal saline (0.05 cc) and 1.5 IU of botulinum toxin A (0.05 cc) (Botox, Allergan, USA) were injected into the dermis layer of the central portion in the proximal one-third of the flap. Gross photographs were taken at days 1, 3, 5 and 7 after the operation. Laser-induced fluorescein fluoroscopy was performed on postoperative day 7 and tissues were retrieved for histological analysis. In addition, reverse transcriptase polymerase chain reaction (RT-PCR) was carried out for quantitative analysis. RESULTS: Gross photos and laser-induced fluorescein fluoroscopy reveal the survival rate of the Botox group was 8.3% higher than the control. In the histologic study, the diameter of vessels is larger and the number of immature vessels is more in the Botox group. The result of RT-PCR shows increased expression of VEGF (vascular endothelial growth factor), CD 31 (PECAM1, platelet/endothelial cell adhesion molecule) and iNOS (inducible nitric oxide synthase), which are considered to be related to vasodilation and endothelial proliferation. CONCLUSION: Our results suggest that botulinum toxin A increases the survival rate of random cutaneous flaps by means of selective suppression of sympathetic neurons of the cutaneous microcirculation system.

Surgical treatment of ossified cephalhematoma.

Cephalhematoma is a collection of blood beneath the periosteum of the bones in the cranial vault. The treatment strategy of most cephalhematoma is conservative. However, in cases of ossified cephalhematoma causing deformities of skull, surgical management is indicated. From 1996 to 2002, the authors treated three cases of ossified cephalhematoma with the suggested pathogenesis of ossification, which cephalhematoma goes to ossification process, rather than calcification. Surgical treatment, which is bony shaving with a burr on the irregular margin site, was performed in one case in which the thickness of the skull in the bulging area was the same as in the normal area in preoperative computed tomography (CT) scan, and a depression did not exist in the operative field. In two cases in which there was any difference in bony density in the preoperative CT scan and depression after removal of cephalhematoma, the bony cap was remodeled into multiple pieces and the depressed region was reconstructed with a remodeled bone cap as an onlay bone graft. There was no evidence of complications and recurrence, and there was good reconstitution of the skull contour in all cases.

Infracture technique for reduction malarplasty with a short preauricular incision.

The infracture technique for reduction malarplasty has been widely used as an aesthetic surgical procedure in northeast Asia. Since 1988, the authors' original method of infracture technique was performed through the combined approach of intraoral and temporopreauricular incision, which may leave a rather long scar on the temporal region. To shorten the external scar, a new technique using a short preauricular incision instead of a long temporopreauricular incision was developed. From September of 2000 to June of 2001, this new approach was applied to 142 patients for correction of prominent zygoma. In this procedure, anteriorly, incomplete fracture of the zygomatic body was performed through an intraoral approach for bending inward. Posteriorly, full-thickness cutting of the zygomatic arch was performed through a preauricular incision. Then, lateral bulging of the zygomatic arch was reduced with infracturing, and the infractured site was fixed in a new position with a microplate and three screws. The advantages of this technique are reduction of the operation time, reduction of the length of the external scar, and reduction of postoperative edema around the operative region. With this combined approach, the authors were able to sufficiently expose the zygomatic arch and body and able to change the lateral convex arch into a concave one. Under direct vision, the authors could effectively and precisely perform the infracture technique through a much shorter preauricular incision that did not result in a long, conspicuous external scar.

Changes in gene cassettes of class 1 integrons among Escherichia coli isolates from urine specimens collected in Korea during the last two decades.

Gene cassettes of class 1 integrons in Escherichia coli isolates from urine specimens collected in Korea during the last 2 decades were characterized. intI1 was detected in 54% of the isolates, yet gene cassette regions were amplified in only 43% of the isolates. intI2 was detected in 29 (5%) isolates, and no intI3 was detected in this study. Twenty-one different genes, including genes encoding resistance to antibiotics, an alcohol dehydrogenase gene (adhE), and unknown genes, were detected. The genes most commonly found in class 1 integrons were those for aminoglycoside and trimethoprim resistance. The occurrence of aminoglycoside resistance genes in class 1 integrons decreased, and the presence of dfr genes increased rapidly, during the last 2 decades. Single-gene cassettes were predominant during the 1980s, while multigene cassettes predominated from the 1990s on. The aadA1, aadA2, and blaP1-aadA2 gene cassettes were frequently found in isolates from the 1980s but were not detected in isolates recovered since 2000. dfrA12-aadA2 and dfrA17-aadA5 were the most prevalent gene cassettes among isolates recovered from the 1990s on. In conclusion, class 1 integrons would appear to be responsible for resistance to antibiotics commonly used to treat urinary tract infections, and selection of a specific gene cassette was found to occur over the course of time.