Evaluation of spironolactone plus hydrochlorothiazide in reducing proteinuria in type 2 diabetic nephropathy

Introduction: Inhibitors of the renin-angiotensin aldosterone system (RAAS) are the basic drugs for treatment of diabetic nephropathy, as to some extent is spironolactone. The aim of the study was to evaluate the effect of spironolactone versus spironolactone plus hydrochlorothiazide in decreasing proteinuria in type 2 diabetic mellitus (T2DM) patients. Methods: In a double-blind clinical trial, 60 T2DM patients with nephropathy randomly assigned to three equal groups were enrolled. Spironolactone (50 mg/day) plus placebo, spironolactone (50 mg/day) plus hydrochlorothiazide (25 mg/day), and hydrochlorothiazide (25 mg/day) plus placebo were prescribed, respectively. The duration of treatment was three months for all patients. Urine protein was measured at the beginning and end of the study and analysis of data was performed. Results: Twenty-six of the patients were male, with a total mean age of 56.88.3 years. Mean 24-h urine protein was reduced in patients in groups 1 and 2 compared to the third group (p < 0.001). Serum potassium in the first group showed a significant increase of 0.26 meq/lit with mean 4.64 +/- 0.28 meq/lit (p=0.002), but it did not change in the second and third groups. Conclusion: Our results showed that spironolactone plus hydrochlorothiazide is an effective and inexpensive modality in the treatment of diabetic nephropathy without increasing serum potassium

Reconfigurable Antennas Based on Plasma Reflectors and Cylindrical Slotted Waveguide

In this chapter, we focus on the application of plasma structures to realize reconfigurable antennas. Several approaches are presented to dynamically control the beamwidth and radiation gain of circularly polarized helical antennas based on plasma reflectors. Ideas and design principles were discussed and confirmed by full-wave simulations and measurements of realized prototypes. It is shown that plasma reflectors can be effectively used to design reconfigurable helicone antennas with controllable gain and beamwidth. The chapter also presents a reconfigurable slotted antenna using a plasma tube inside the metallic waveguide. It is shown that the radiation pattern of the antenna can be readily reconfigured by changing the state of the plasma column. In short, it is shown that in contrast to conventional methods based on electronic or mechanical devices, reconfigurable antennas based on plasma media benefit from simple and relatively low-cost structures as well as high performance

Two-dimensional displacement and alignment sensor based on reflection coefficients of open microstrip lines loaded with split ring resonators

A two-dimensional displacement and alignment sensor is proposed based on two open-ended transmission lines, each loaded with a split ring resonator (SRR). In this arrangement, the depth of resonance-induced notches in the reflection coefficients can be used to sense a displacement of the loading SRRs in two orthogonal directions. Since the operation principle of the sensor is based on the symmetry properties of SRR-loaded transmission lines, the proposed sensor benefits from immunity to variations in ambient conditions. More importantly, it is shown that in contrast to previously published metamaterial-inspired two-dimensional displacement and alignment sensors, the proposed sensor can be operated at a single fixed frequency. The concept and simulation results are validated through measurement

S-shaped complementary split ring resonators and their application to compact differential bandpass filters with common-mode suppression

This letter presents an S-shaped complementary split ring resonator (S-CSRR) for application in compact differential filters. The working principle of the proposed S-CSRR is explained and a circuit model is developed and validated through electromagnetic simulations. It is shown that an S-CSRR-loaded differential microstrip line with series gaps can be used in the design of compact differential bandpass filters (BPFs) with common-mode suppression. The filter design procedure is explained and the theoretical concept is validated through fabrication and measurement of a compact (0.09 λg 0.25 λg) third-order differential BPF with common-mode suppression

Two-dimensional alignment and displacement sensor based on movable broadside-coupled split ring resonators

This paper proposes a two-dimensional alignment and displacement sensor based on movable broadside-coupled split ring resonators (BC-SRRs). As a basis for this sensor, a one-dimensional displacement sensor based on a microstrip line loaded with BC-SRRs is presented firstly. It is shown that compared to previously published displacement sensors, based on SRR-loaded coplanar waveguides, the proposed one-dimensional sensor benefits from a much wider dynamic range. Secondly, it is shown that with modifications in the geometry of the BC-SRRs, the proposed one-dimensional sensor can be modified and extended by adding a second element to create a high-dynamic range two-dimensional displacement sensor. Since the proposed sensors operate based on a split in the resonance frequency, rather than the resonance depth, they benefit from a high immunity to environmental noise. Furthermore, since the sensors' principle of operation is based on the deviation from symmetry, they are more robust to ambient conditions such as changes in the temperature, and thus they can be used as alignment sensors as well. A prototype of the proposed two-dimensional sensor is fabricated and the concept and simulation results are validated through experiment

Metamaterial-inspired structures and their applications in microwave, millimeter-wave and terahertz planar circuits.

Metamaterials are generally defined as periodic composite structures that are engineered to modify the electromagnetic properties of materials, especially in order to achieve new physically realizable responses that may not be readily available in nature. The key to the application of metamaterial resonators for the synthesis of such effective media is their small electrical size. This feature can be also exploited for the miniaturization of planar circuits. Motivated by the need for miniaturized planar structures in mobile wireless systems, metamaterial-inspired structures are proposed throughout this thesis for the design of compact microwave, millimeter-wave and terahertz planar structures with improved performance. The thesis firstly proposes slow-wave and SRR-loaded coplanar strips resonators for the design of compact high quality factor balanced resonators for 60GHz VCOs in CMOS technology. Next, the thesis is focused on the miniaturization of microwave filters either by proposing resonators with dual-band functionality or through modifying the shape of metamaterial resonators. Shape modifications of metamaterial resonators are also used for the design of high-dynamic-range one- and two-dimensional displacement sensors as well as of a rotation sensor with improved dynamic range. It is further shown that high level of miniaturization can be achieved in a single-layer S-shaped SRR (S-SRR), if the loops of the S-SRR are excited by contra-directional magnetic fluxes, which makes the S-SRR very well suited for application in coplanar waveguide (CPW) technology. The thesis also proposes the dual counterpart of the S-shaped SRR, i.e., S-shaped complementary split ring resonator (S-CSRR) for application in the design of compact differential bandpass filters with inherent common-mode suppression. Finally, the application of SRRs to the design of compact bandpass filters for terahertz surface waves on single wire waveguides—the so-called planarGoubau lines (PGLs)—is studied numerically and experimentally. The results of this research show the versatility and potential of metamaterial-inspired resonators for the realization of miniaturized structures in planar technologies in different frequency bands.Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 201

Beam-Steerable Helical Antenna Using Plasma Reflectors

International audienceThe aim of this paper is to investigate the steering mechanism of the beam pattern of a helical antenna using a half-cup plasma reflector. To this end, variations of the radiation characteristics and also the direction of the main beam of the antenna due to changes in the dimensions of the half-cup plasma reflector, including its diameter and height, are numerically computed and analyzed. The simulation results show that using this structure, the beam direction can be altered in 3-D space within a solid angle of +/- 10 degrees. Also, it is highlighted that the half-cup plasma reflector may adversely affect the polarization of the helical antenna. Therefore, a trade-off between polarization and performance of an antenna based on a parametric study has to be made. Thus, in this investigation, the axial ratio of the antenna is also analyzed for each dimension. For demonstration, the study is used for the design of a circularly polarized helical antenna with a half-cup plasma reflector. Good agreement between the numerically calculated and measured results validates the presented study

Two-dimensional displacement and alignment sensor based on reflection coefficients of open microstrip lines loaded with split ring resonators

A two-dimensional displacement and alignment sensor is proposed based on two open-ended transmission lines, each loaded with a split ring resonator (SRR). In this arrangement, the depth of resonance-induced notches in the reflection coefficients can be used to sense a displacement of the loading SRRs in two orthogonal directions. Since the operation principle of the sensor is based on the symmetry properties of SRR-loaded transmission lines, the proposed sensor benefits from immunity to variations in ambient conditions. More importantly, it is shown that in contrast to previously published metamaterial-inspired two-dimensional displacement and alignment sensors, the proposed sensor can be operated at a single fixed frequency. The concept and simulation results are validated through measurement

Angular Displacement and Velocity Sensors Based on Coplanar Waveguides (CPWs) Loaded with S-Shaped Split Ring Resonators (S-SRR)

In this paper, angular displacement and angular velocity sensors based on coplanar waveguide (CPW) transmission lines and S-shaped split ring resonators (S-SRRs) are presented. The sensor consists of two parts, namely a CPW and an S-SRR, both lying on parallel planes. By this means, line-to-resonator magnetic coupling arises, the coupling level being dependent on the line-to-resonator relative angular orientation. The line-to-resonator coupling level is the key parameter responsible for modulating the amplitude of the frequency response seen between the CPW ports in the vicinity of the S-SRR fundamental resonance frequency. Specifically, an amplitude notch that can be visualized in the transmission coefficient is changed by the coupling strength, and it is characterized as the sensing variable. Thus, the relative angular orientation between the two parts is measured, when the S-SRR is attached to a rotating object. It follows that the rotation angle and speed can be inferred either by measuring the frequency response of the S-SRR-loaded line, or the response amplitude at a fixed frequency in the vicinity of resonance. It is in addition shown that the angular velocity can be accurately determined from the time-domain response of a carrier time-harmonic signal tuned at the S-SRR resonance frequency. The main advantage of the proposed device is its small size directly related to the small electrical size of the S-SRR, which allows for the design of compact angular displacement and velocity sensors at low frequencies. Despite the small size of the fabricated proof-of-concept prototype (electrically small structures do not usually reject signals efficiently), it exhibits good linearity (on a logarithmic scale), sensitivity and dynamic range