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The demand and urgency of new drug design and discovery is facing new challenges in the wake of spread and persistence of serious global threat of antibiotic resistance. One of the major hurdles in the development of new drugs that are more aqueous soluble and passively diffusible is the paucity of knowledge regarding their physicochemical interactions with biological membranes. Being chemical-mimics of biomembranes, surfactant-based micellar systems present excellent pseudo-membrane models to study biophysical interactions of drugs with biological membranes in vitro. The present research focuses on physicochemical interaction of sulfamethoxazole (SMZ) alone and in combination with trimethoprim (TMP) with cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS). UV–visible spectroscopy, electrical conductivity and cyclic voltammetric techniques were employed to quantitate different drug-surfactant interaction parameters. UV–visible spectroscopic was used to evaluate critical micelle concentration (CMC) of CTAB and SDS in the presence of SMZ, TMP and their binary mixture in aqueous medium (pH 7.0). Differential absorption technique was used to determine partition coefficient (Kc) and binding constant (Kb) of SMZ and (SMZ + TMP) mixture with ionic micelles. Thermodynamic parameters of micellization such as Δ H m o , Δ S m o , and Δ G m o of CTAB and SDS in the presence SMZ and its mixed form with TMP were calculated in deionized water. Further, voltammetric investigations depict the strong binding of SMZ and its TMP mixture with CTAB micelles relative to SDS micelles. The effect of concentration of surfactant on the conductivities (κ) of sulphamethoxazole at different temperatures in deionized water; (a) SDS; (b) CTAB [ABSTRACT FROM AUTHOR]

Circular polarized (CP) antennas are well suited for long-distance transmission attainment. In order to be adaptable for beyond 5G communication, a detailed and systematic investigation of their important conventional features is required for expected enhancements. The existing designs employing millimeter wave, microwave, and ultra-wideband (UWB) frequencies form the elementary platform for future studies. The 3.4â€"3.8 GHz frequency band has been identified as a worthy candidate for 5G communications because of spectrum availability. This band comes under UWB frequencies (3.1â€"10.6 GHz). In this survey, a review of CP antennas in the selected areas to improve the understanding of early-stage researchers specially experienced antenna designers has presented for the first time as best of our knowledge. Design implementations involving size, axial ratio, efficiency, and gain improvements are covered in detail. Besides that, various design approaches to realize CP antennas including (a) printed CP antennas based on parasitic or slotted elements, (b) dielectric resonator CP antennas, (c) reconfigurable CP antennas, (d) substrate integrated waveguide CP antennas, (e) fractal CP antennas, (f) hybrid techniques CP antennas, and (g) 3D printing CP antennas with single and multiple feeding structures have investigated and analyzed. The aim of this work is to provide necessary guidance for the selection of CP antenna geometries in terms of the required dimensions, available bandwidth, gain, and useful materials for the integration and realization in future communication systems. [ABSTRACT FROM AUTHOR]

This work presents the development and validation of a simple, rapid, and cost-effective spectrophotometric method for quantitative analysis of uric acid in biological samples. The method relies upon uric acid-led reduction of Fe(III) to Fe(II) of sample/standard solutions which stoichiometrically engages ferrozine to form a magenta-colored complex. Different parameters including pH, metal and chelator concentrations, temperature, etc., were optimized for the maximum intensity and stability of the complex. The uric acid concentrations of synthetic/plasma solutions were determined by comparing the color intensity of Fe(ferrozine)32+ complex produced by test solution with the standard curve formed by known uric acid concentrations. The method was validated in accordance with ICH guidelines and subjected to human plasma analysis. The results obtained were compared with a reference (enzymatic) method which revealed that there was no significant difference between the two methods at 95% confidence level. The method is highly specific, precise, linear, accurate, and robust. An economical and validated colorimetric method based on reduction of Fe(III) to Fe(II) by uric acid in sample/standard solutions which stoichiometrically combines with ferrozine to form a colored complex, is reported for estimation of uric acid in pure and biological samples. [ABSTRACT FROM AUTHOR]

In this article, a novel design of patch antenna with wide band characteristics is presented. The proposed antenna is having electrical dimensions of 0.14λ×0.11λ (at lower initial frequency) and footprints of 150 mm2. Structural parameters optimization shows 3.1-23.5 GHz frequency range for a (reflection coefficient) S11 ≤ -10 dB and simulated gain 6.8 dB is obtained. An equivalent circuit model is proposed to get an insight view of antenna. Advanced Systems Design (ADS) simulation results are obtain which confirm the validity of proposed model. Degenerated foster canonical form has been used to explain the reactance and capacitive behavior idea of simulated proposed antenna's input impedance later on an equivalent circuit model and smith chart is also suggested. HFSS and CST have been used to analyze antenna behavior. The proposed antenna can be further used for microwave image detection applications. [ABSTRACT FROM AUTHOR]

A low quiescent current 180-nm output-capacitorless low-dropout regulator with small-gain stages (SGSs) is presented in this paper. The proposed technique permits the regulator to distribute the load current into two power transistors depending on the demand of the load using a controller based on load variation criterion. SGSs are introduced to enhance loop gain without low-frequency poles. The proposed architecture does not require compensation capacitor. Thus, the active chip area is reduced to 73.59 µm × 36 µm. The measured results have shown that the fabricated circuit consumes a quiescent current of 1.8 µA at no load, regulating the output at 1 V with maximum output current of 50 mA from a voltage supply of 1.2 V. It achieves full range stability from 0 to 50 mA load current at a maximum 100 pF load capacitor. [ABSTRACT FROM AUTHOR]