Image-Based Flow Cytometry and Angle-Resolved Light Scattering to Define the Sickling Process.

Red blood cells (RBCs) from sickle cell patients exposed to a low oxygen tension reveal highly heterogeneous cell morphologies due to the polymerization of sickle hemoglobin (HbS). We show that angle-resolved light scattering approach with the use of image-based flow cytometry provides reliable quantitative data to define the change in morphology of large populations of RBCs from sickle cell patients when the cells are exposed for different times to low oxygen. We characterize the RBC morphological profile by means of a set of morphological and physical parameters, which includes cell shape, size, and orientation. These parameters define the cell as discocyte, sickle, elongated, as well as irregularly or abnormal RBC shaped cells, including echinocytes, holly-leaf, and granular structures. In contrast to microscopy, quick assessment of large numbers of cells provides statistically relevant information of the dynamic process of RBC sickling in time. The use of this approach facilitates the understanding of the processes that define the propensity of sickle blood samples to change their shape, and the ensuing vaso-occlusive events in the circulation of the patients. Moreover, it assists in the evaluation of treatments that include the use of anti-sickling agents, gene therapy-based hemoglobin modifications, as well as other approaches to improve the quality of life of sickle cell patients. © 2019 International Society for Advancement of Cytometry.

Light-controlled photonics-based mm-wave beam switch.

We present experimental investigation of light-controlled photonics-enhanced quasi-optical mm-wave beam switch operating at a resonant frequency in the mm-wave band of 75 to 110 GHz. The switch is implemented as a Bragg structure with a resonant layer of high-resistivity silicon that creates a narrow transmission peak within the mm-wave propagation gap. The peak amplitude is sensitive to the intensity of light pulses illuminating the structure. When using a silicon wafer of 30 KOhm · cm resistivity and light pulses created by a 400W LED-array light source, we achieved mm-wave transmission peak modulation exceeding 15 dB.

A Wireless Passive Sensing System for Displacement/Strain Measurement in Reinforced Concrete Members.

In this study, we show a wireless passive sensing system embedded in a reinforced concrete member successfully being employed for the measurement of relative displacement and strain in a simply supported beam experiment. The system utilizes electromagnetic coupling between the transceiver antenna located outside the beam, and the sensing probes placed on the reinforcing bar (rebar) surface inside the beam. The probes were designed in the form of a nested split-ring resonator, a metamaterial-based structure chosen for its compact size and high sensitivity/resolution, which is at µm/microstrains level. Experiments were performed in both the elastic and plastic deformation cases of steel rebars, and the sensing system was demonstrated to acquire telemetric data in both cases. The wireless measurement results from multiple probes are compared with the data obtained from the strain gages, and an excellent agreement is observed. A discrete time measurement where the system records data at different force levels is also shown. Practical issues regarding the placement of the sensors and accurate recording of data are discussed. The proposed sensing technology is demonstrated to be a good candidate for wireless structural health monitoring (SHM) of reinforced concrete members by its high sensitivity and wide dynamic range.

Wireless measurement of elastic and plastic deformation by a metamaterial-based sensor.

We report remote strain and displacement measurement during elastic and plastic deformation using a metamaterial-based wireless and passive sensor. The sensor is made of a comb-like nested split ring resonator (NSRR) probe operating in the near-field of an antenna, which functions as both the transmitter and the receiver. The NSRR probe is fixed on a standard steel reinforcing bar (rebar), and its frequency response is monitored telemetrically by a network analyzer connected to the antenna across the whole stress-strain curve. This wireless measurement includes both the elastic and plastic region deformation together for the first time, where wired technologies, like strain gauges, typically fail to capture. The experiments are further repeated in the presence of a concrete block between the antenna and the probe, and it is shown that the sensing system is capable of functioning through the concrete. The comparison of the wireless sensor measurement with those undertaken using strain gauges and extensometers reveals that the sensor is able to measure both the average strain and the relative displacement on the rebar as a result of the applied force in a considerably accurate way. The performance of the sensor is tested for different types of misalignments that can possibly occur due to the acting force. These results indicate that the metamaterial-based sensor holds great promise for its accurate, robust and wireless measurement of the elastic and plastic deformation of a rebar, providing beneficial information for remote structural health monitoring and post-earthquake damage assessment.

Wireless displacement sensing enabled by metamaterial probes for remote structural health monitoring.

We propose and demonstrate a wireless, passive, metamaterial-based sensor that allows for remotely monitoring submicron displacements over millimeter ranges. The sensor comprises a probe made of multiple nested split ring resonators (NSRRs) in a double-comb architecture coupled to an external antenna in its near-field. In operation, the sensor detects displacement of a structure onto which the NSRR probe is attached by telemetrically tracking the shift in its local frequency peaks. Owing to the NSRR's near-field excitation response, which is highly sensitive to the displaced comb-teeth over a wide separation, the wireless sensing system exhibits a relatively high resolution (<1 µm) and a large dynamic range (over 7 mm), along with high levels of linearity (R2 > 0.99 over 5 mm) and sensitivity (>12.7 MHz/mm in the 1-3 mm range). The sensor is also shown to be working in the linear region in a scenario where it is attached to a standard structural reinforcing bar. Because of its wireless and passive nature, together with its low cost, the proposed system enabled by the metamaterial probes holds a great promise for applications in remote structural health monitoring.

Characterization of volatile constituents from Origanum onites and their antifungal and antibacterial activity.

Essential oils obtained by hydrodistillation (HD) and microwave-assisted HD (MWHD) of Origanum onites aerial parts were analyzed by GC and GCIMS. Thirty-one constituents representing 98.6% of the water-distilled oil and 52 constituents representing 99.6% of the microwave-distilled oil were identified. Carvacrol (76.8% HD and 79.2% MWHD) and thymol (4.7% HD and 4.4% MWHD) were characterized as major constituents in both essential oils. Separation of carvacrol and thymol was achieved by overpressured layer chromatography. HPTLC and TLC separations were also compared. Essential oils were evaluated for antifungal activity against the strawberry anthracnose-causing fungal plant pathogens Colletotrichum acutatum, C. fragariae, and C. gloeosporioides using a direct overlay bioautography assay. Furthermore, main oil components carvacrol and thymol were then evaluated for antifungal activity; only carvacrol demonstrated nonselective antifungal activity against the three Colletotrichum species. Thymol and carvacrol were subsequently evaluated in a 96-well microdilution broth assay against Phomopsis obscurans, Fusarium oxysporum, three Colletotrichum species, and Botrytis cinerea. No activity was observed against any of the three Colletotrichum species at or below 30 pM. However, thymol demonstrated antifungal activity and produced 31.7% growth inhibition of P. obscurans at 120 h and 0.3 pM, whereas carvacrol appeared inactive. Thymol and carvacrol at 30 pM showed 51.5 and 36.9% growth inhibition of B. cinerea at 72 h. The mechanism of antibacterial activity was studied in a bioautography-based BioArena system. Thymol and carvacrol showed similar inhibition/killing effect against Bacillus subtilis soil bacteria; the action could be enhanced by the formaldehyde generator and transporter copper (II) ions and could be decreased in the presence of L-arginine, a formaldehyde capturer. Results indicated that Origanum essential oils and its major components thymol and carvacrol appear to generate antimicrobial activity through a mechanism of action where formaldehyde and its reaction products are produced.

The effect of stinging nettle (Urtica dioica) seed oil on experimental colitis in rats.

This study investigated the effect of Urtica dioica, known as stinging nettle, seed oil (UDO) treatment on colonic tissue and blood parameters of trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. Experimental colitis was induced with 1 mL of TNBS in 40% ethanol by intracolonic administration with a 8-cm-long cannula with rats under ether anesthesia, assigned to a colitis group and a colitis+UDO group. Rats in the control group were given saline at the same volume by intracolonic administration. UDO (2.5 mL/kg) was given to the colitis+UDO group by oral administration throughout a 3-day interval, 5 minutes later than colitis induction. Saline (2.5 mL/kg) was given to the control and colitis groups at the same volume by oral administration. At the end of the experiment macroscopic lesions were scored, and the degree of oxidant damage was evaluated by colonic total protein, sialic acid, malondialdehyde (MDA), and glutathione levels, collagen content, tissue factor activity, and superoxide dismutase and myeloperoxidase activities. Colonic tissues were also examined by histological and cytological analysis. Pro-inflammatory cytokines (tumor necrosis factor-α, interleukin-1ß, and interleukin-6), lactate dehydrogenase activity, and triglyceride and cholesterol levels were analyzed in blood samples. We found that UDO decreased levels of pro-inflammatory cytokines, lactate dehydrogenase, triglyceride, and cholesterol, which were increased in colitis. UDO administration ameliorated the TNBS-induced disturbances in colonic tissue except for MDA. In conclusion, UDO, through its anti-inflammatory and antioxidant actions, merits consideration as a potential agent in ameliorating colonic inflammation.

Low-threshold lasing eigenmodes of an infinite periodic chain of quantum wires.

We study the lasing eigenvalue problems for a periodic open optical resonator made of an infinite grating of circular dielectric cylinders standing in free space, in the E- and H-polarization modes. If possessing a "negative-absorption" refractive index, such cylinders model a chain of quantum wires made of the gain material under pumping. The initial-guess values for the lasing frequencies are provided by the plane-wave scattering problems. We demonstrate a new effect: the existence of specific grating eigenmodes that have a low threshold of lasing even if the wires are optically very thin.

Integral equation analysis of an arbitrary-profile and varying-resistivity cylindrical reflector illuminated by an E-polarized complex-source-point beam.

A two-dimensional reflector with resistive-type boundary conditions and varying resistivity is considered. The incident wave is a beam emitted by a complex-source-point feed simulating an aperture source. The problem is formulated as an electromagnetic time-harmonic boundary value problem and cast into the electric field integral equation form. This is a Fredholm second kind equation that can be solved numerically in several ways. We develop a Galerkin projection scheme with entire-domain expansion functions defined on an auxiliary circle and demonstrate its advantage over a conventional moment-method solution in terms of faster convergence. Hence, larger reflectors can be computed with a higher accuracy. The results presented relate to the elliptic, parabolic, and hyperbolic profile reflectors fed by in-focus feeds. They demonstrate that a partially or fully resistive parabolic reflector is able to form a sharp main beam of the far-field pattern in the forward half-space; however, partial transparency leads to a drop in the overall directivity of emission due to the leakage of the field to the shadow half-space. This can be avoided if only small parts of the reflector near the edges are made resistive, with resisitivity increasing to the edge.

Physical optics modeling of 2D dielectric lenses.

We propose an advanced physical optics formulation for the accurate modeling of dielectric lenses used in quasi-optical systems of millimeter, submillimeter, and infrared wave applications. For comparison, we obtain an exact full-wave solution of a two-dimensional lens problem and use it as a benchmark for testing and validation of asymptotic models being considered.

Numerical analysis and synthesis of 2D quasi-optical reflectors and beam waveguides based on an integral-equation approach with Nystrom's discretization.

Considered is the beam wave guidance and scattering by 2D quasi-optical reflectors modeling the components of beam waveguides. The incident field is taken as the complex-source-point field to simulate a finite-width beam generated by a small-aperture source. A numerical solution is obtained from the coupled singular integral equations (SIEs) for the surface currents on reflectors, discretized by using the recently introduced Nystrom-type quadrature formulas. This analysis is applied to study what effect the edge illumination has on the performance of a chain of confocal elliptic reflectors. We also develop a semianalytical approach for shaped reflector synthesis after a prescribed near-field pattern. Here a new point is the use of auxiliary SIEs of the same type as in the scattering analysis problem, however, for the gradient of the objective function. Sample results are presented for the synthesis of a reflector-type beam splitter.

Evaluation of internal MRI coils using ultimate intrinsic SNR.

The upper bounds of the signal-to-noise ratio (also known as the "ultimate intrinsic signal-to-noise ratio" (UISNR)) for internal and external coils were calculated. In the calculation, the body was modeled as a dielectric cylinder with a small coaxial cylindrical cavity in which internal coils could be placed. The calculated UISNR values can be used as reference solutions to evaluate the performance of internal MRI coils. As examples, we evaluated the performance of a loopless antenna and an endourethral coil design by comparing their ISNR with the UISNR.