Compact Band Research Articles

Novel green HPTLC and organic solvent-free micellar LC methods for the simultaneous determination of Ozenoxacin and benzoic acid; greenness assessment and applications

Ozenoxacin (OZ) is a novel synthetic quinolone antimicrobial agent that has been recently approved by US-FDA for the treatment of impetigo in combination with its preservative, benzoic acid (BA). Meanwhile, implementing greener chromatography has been a recent goal of a great ecological importance. In the proposed research, two novel green methods have been validated for the simultaneous determination of OZ and BA in skin creams for the first time. An organic-solvent free mixed-micellar HPLC technique was developed using RP-C8 core-shell column with a mobile phase consisting of 0.01 M Brij-35, 0.15 M sodium dodecyl sulfate, and 0.02 M ammonium acetate in water, adjusted to pH 4.5. The mobile phase flow rate was 1 mL min−1 and detecting analytes in short retention times (3.4 and 4.7 min for BA and OZ, respectively) at wavelength 235 nm. The working concentration ranges were 1–10 and 10–100 μg mL−1 for BA and OZ, respectively. Another eco-friendly high-performance thin-layer chromatography (HPTLC) method was designed using HPTLC silica-gel 60 F254 plates as a stationary phase and ethyl acetate–ethanol–ammonia (6:4:2, v/v/v) as mobile phase. The detection was also performed at λmax = 235 nm. The method was found linear across concentration range of 0.5–1.8 and 0.05–0.18 μg/band for OZ and BA, respectively which gave symmetric, compact band with Rf values of 0.21 and 0.69 for OZ and BA, respectively. The proposed methods were applied successfully in their combined marketed pharmaceutical cream. The proposed methods were typically based on safe biodegradable reagents, and their ecological superiority was proven using recent greenness metrics.

Second-Order Work Criterion in the Stability Analysis of an Earth Dam Subjected to Seepage

Abstract Failure may take different forms: reaching the Mohr–Coulomb limit stress condition is accompanied by yielding, strain localisation may occur in shear, compaction or dilatant bands, arbitrary large strain and loss of strength may be accompanied by a field of chaotic displacements of soil particles. Failure is also related to material instability. It takes place when there is a loss of uniqueness of constitutive relationships. It has been found that instability domains exist strictly inside the Mohr–Coulomb failure surface. Material instability can be detected by local Hill's criterion, that is the second-order work at a point. Results of a coupled hydro-mechanical finite element analysis of an ‘earth dam – subgrade’ system at changing hydraulic boundary conditions have been presented in the article. Normalised values of the second-order work and factor of safety values by the shear strength reduction procedure for corresponding stages of the analysis were calculated. It has been shown that the value of the safety factor corresponds to the values of the second-order work. The analysis results show that a decrease in the value of the safety factor is accompanied by a decrease in the value of the second-order work until negative values occur at some points.

Modeling heterogeneity and permeability evolution in a compaction band using a phase-field approach

Compaction bands are tabular zones of localized compressive deformation associated with porosity and permeability reduction. Depending on their orientation, compaction bands can act as barriers to fluid flow, and can be detrimental to fluid production in oil and gas reservoirs, as well as in CO2 sequestration. The process of permeability reduction and the development of excess pore pressures during compaction band formation in a heterogeneous rock mass are not fully understood. Furthermore, few studies have modeled compaction band formation considering coupled hydromechanical processes. In this study, we propose a coupled hydromechanical, phase-field approach for capturing the formation and propagation of compaction bands in heterogeneous porous media. Breakage mechanics is adopted to characterize the free energy function in the intact and damaged material. The resulting phase-field variable provides a measure of the degree of grain crushing. Permeability reduction in the zone of compaction localization is modeled using the Kozeny–Carman equation accounting for microstructural evolution. Numerical simulations demonstrate the ability of the model to capture compaction band formation, porosity reduction, and permeability evolution under drained and undrained conditions. The results highlight the role of effective confining pressure, drainage conditions, and material parameters on the styles of compaction bands that form.

Compact dual band 4-port MIMO antenna for 5G-sub 6 GHz/N38/N41/N90 and WLAN frequency bands

In this investigation, a dual-band 4 port MIMO antenna is designed, fabricated and measured. The MIMO design consists of perturbed hexagonal patch along its periphery on the top of the substrate and the connected ground plane on the bottom. The MIMO design has an overall dimension of 50 × 50 × 0.8 mm3. The proposed antenna structure demonstrates the dual frequency band of 2.47–3.38 GHz and 4.94–7.24 GHz, respectively covering the 5G sub-6 GHz/WLAN/HiperLAN band applications. Moreover, the radiation efficiency, gain and far-field patterns are also presented across both the operating bands. The antenna diversity parameters which include ECC, DG, MEG, CCL and TARC are studied and found excellent for the MIMO antenna implementation. The channel loss of the proposed 4 × 4 MIMO antenna is calculated and found 21.54 b/s/Hz at SNR of 20 dB. The proposed design is modeled in CST Microwave Studio and the results are compared with the fabricated prototype antenna for the practical implementations.

Reduced flow model and transmissibility upscaling in multi-layered faulted reservoirs

We construct a new three-scale model for single phase incompressible flow in faulted rocks containing multiple damage zones. At the finer scale (O(1m)), flow is influenced by the high-contrast layered heterogeneities inherent to the core and adjacent damage zones, which are populated by geological anomalies, such as compaction bands, debris, and fine sediments and joints. In the first stage of the reiterated homogenization procedure, we construct a lower-dimensional reduced model, where the discontinuity is envisioned as (n−1)-dimensional manifold (n=2,3), topologically attached to multiple layered structures, with flow patterns characterized by various jumps in pressure and velocity fields. Subsequently, by aligning the fault with the interface between adjacent simulation cells of a coarse grid, the upscaling of the reduced flow model gives rise to transmissibility multipliers, whose constitutive response stems naturally from the local flow patterns, exhibiting improved accuracy compared to the traditional harmonic mean, inherent to the two-point flux approximation. Computational simulations obtained with the finite element method with localized discontinuous spaces illustrate the ability of the three-scale model to provide further insight into the behavior of the transmissibility multipliers, which capture the effects of fault zone texture upon the flow discretization. The methodology proposed herein shows enormous potential for the development of more accurate transmissibility preprocessors at relatively low computational costs, consequently overcoming the shortcomings of a direct application of the local high-fidelity approach.

Polarization–Insensitive Angularly Stable Compact Triple Band Stop Frequency Selective Surface for Shielding Electromagnetic Radiations

Polarization–Insensitive Angularly Stable Compact Triple Band Stop Frequency Selective Surface for Shielding Electromagnetic Radiations

Design of a Validated HPTLC Methodology for the Measurement of Linoleic and Oleanolic Acid in Eclipta alba

Eclipta alba (Asteraceae family) is a widely recognized medicinal plant found in tropical and subtropical regions of the world. It is one of the plants that is most frequently utilized in traditional medical systems, including Ayurveda, Siddha, Homeopathy, Unani, and folk medicine. Many significant phytochemical components, including triterpenes, flavonoids, coumestans, steroids, saponins, and polypeptides, are present in each portion of this medicinal plant. Several herbal and ayurvedic formulations, like Indulekha bringha oil and Liv.52 Gnx pill, contain E. alba as an important therapeutic ingredient. The objective of the current work was to create a validated and consistent HPTLC technique for the simultaneous measurement of linoleic acid and oleanolic acid in E. alba. The procedure used silica gel 60 F254 as the stationary phase and ethyl acetate, toluene, and formic acid at a ratio of 4:7:0.2 (v/v/v) as the mobile phase, which produced compact bands upon derivatization with anisaldehyde-sulfuric acid reagent. The correlation coefficient (r2) for the linear regression data for the standard linoleic and oleanolic acids calibration curves was 0.9966 and 0.9964, respectively, and it demonstrated a good linear relation over a range of concentrations of 300-1500 ng/spot and 450–1600 ng/spot with respect to the area. The approach’s precision, accuracy, robustness, and selectivity were all assessed. LoD and LoQ for linoleic and oleanolic acids were measured to be 108.47 and 182.33 ng/spot and 258.30 and 327.54 ng/spot, respectively. We came to the conclusion that this approach, which uses HPTLC to quantify linoleic and oleanolic acids, is effective, straightforward, accurate, and reproducible

An optically transparent dual-band frequency selective surface for polarization independent RF shielding

This article reports on a compact dual band, Frequency Selective Surface (FSS) based spatial filter for Wi-Fi and WLAN shielding applications on a transparent glass surface with optical transparency of 70%. The unit cell comprises an outer square loop resonator with a disconnected and concentric annular ring resonator. To introduce frequency tuning and compactness T shape stubs are strategically loaded on these resonators and it is ensured that the mutual coupling remains minimal. The outer square resonator suppresses the 2.4 GHz band, and the inner circular ring resonator stops the 5.4 GHz band. The unit element is four-fold symmetric thus it offers complete polarization independence. A detailed parametric and electromagnetic field analysis has been conducted to elucidate the significance of different sections of the unit element. An equivalent lumped circuit model is also derived for the proposed unit element to better explain the underlying working mechanism. A finite prototype of 15 × 11 elements is fabricated on a soda lime float glass by using ordinary adhesive copper foils with a standard chemical etching process. Polarization independence and angular stability up to 45° are measured and compared with the simulated responses. The FSS shield offers frequency suppression up to 45 dB and 43 dB for 2.4 GHz and 5.4 GHz bands respectively. With high optical transparency, the design allows maximum light through it and causes no extra burden on energy consumption for indoor applications. The compact dual band design and the possibility of direct application on host surfaces like glass windows and doors make this design an excellent candidate for data security and privacy applications in secure installations with an esthetically pleasing outlook.

Defected ground structure based compact UWB dielectric resonator antennas with enhanced bandwidth

Abstract This article introduces two new compact ultra-wide band (UWB) rectangular dielectric resonator antennas (RDRAs) with enhanced bandwidth (BW), gain, and directivity. The RDRAs are designed at 10 GHz resonant frequency. The proposed RDRAs are compactly designed using resonating dielectric material (RDM) of Alumina_96 pct (ε r = 9.4, tanδ = 0.006) with overall dimensions of 30 × 20 × 4.6 mm3. The RDMs are mounted on FR4 substrate (ε r = 4.4, tanδ = 0.02) with defected ground structure (DGS). The DGS are comprised of rectangular and circular ring slots on it. These compact DGS-RDRAs provides enhanced BW. Prototypes of the two suggested RDRAs are fabricated. The fabricated RDRAs are validated by experimental set-ups. The RDRA with rectangular-ring slot DGS provides impedance BW (S 11 < −10 dB) of 33.97 % (8.6658–12.071 GHz). The impedance BW of the other RDRA is 27.97 % (9.08–11.869 GHz). The rectangular-ring slotted RDRA offers radiation efficiency and peak realized gain of 86.4 % and 6.27 dBi, respectively within the band of operating frequencies. The radiation efficiency and realised gain of circular-ring slotted RDRA are 86.18 % and 5.9 dBi, respectively. Good agreements are achieved in between the simulated results and measured results. The results are compared with some recently developed antennas available in literature. The comparison shows that the proposed RDRAs can be suitable candidate for various X-band applications such as satellite downlinks, synthetic aperture radar, weather monitoring by military and some government organizations.

Compact eight-shaped ISM-I band wearable antenna for wireless body area network applications

Abstract The design and analysis of the electrically small eight-shaped wearable antenna for both on- and off-body communication is proposed in this paper. An eight-shaped radiating structure is placed over the jeans substrate and an I-shaped slot is introduced in the ground plane which makes the antenna resonates at the ISM-I band (2.4 GHz). The antenna has a compact size of 0.30λ 0 × 0.20λ 0 × 0.001λ 0, where λ 0 is the free space wavelength at the resonance frequency. The impedance bandwidth (≤−10 dB) of the antenna is 6.1 % and 5.8 % in free space and presence of a human body phantom respectively. The antenna design exhibits good gain along with an improved omnidirectional radiation pattern. The specific absorption rate (SAR) of the antenna averaged over 1 g of tissue is 0.21 W/kg at 2.45 GHz which is far below the FCC standard. The paper also discusses the bending analysis and the fundamental size limitations of the small antenna, concluding that it is suitable for practical use. The simulated results of the prototype are validated by the measured results.

A Compact Penta Band Notched UWB Antenna Using Modified U-Slots and EBG Structures

The proposed compact Ultra-Wide Band (UWB) antenna is having the ability to reject five bands operating in UWB and it is having a rectangular monopole antenna. To achieve the required Penta band notch characteristics and the multi operational bands, two square shaped mushroom type EBG’s are placed in the vicinity of the feedline and three modified U-Shaped Slots are etched on the radiating surface. The two-mushroom type EBG’s are responsible for attaining two notch bands at 3.5 GHz (3.38-3.6 GHz, Wi-MAX), 5.0 GHz (4.85-5.18GHz, lower WLAN) and modified U-Shaped slots are responsible for attaining three notch bands at 2.5 GHz (2.3-2.67 GHz, ISM band), 3.0 GHz (2.8-3.08 GHz, Radar surveillance band), 4.0 GHz (3.88-4.1 GHz, C-band satellite downlink). The step wise implementation of the Penta notch band UWB antenna along with the relative analysis is discussed. The results show that the proposed antenna is a very good one for UWB applications which requires multi operational bands with selective band rejections.

Constitutive modeling of a laumontite-rich tight rock and the application to poromechanical analysis of deeply drilled wells

Geological formations containing laumontite-rich rock are usually treated as problematic for geo-energy production projects because the presence of laumontite mineral can promote complex mechanical behaviors. Previous laboratory results indicate that rock formations with a higher laumontite content display severe stress sensitivity in poromechanical responses. With an increase in confining pressure, there is a transition from dilation to compression regime and the resulting localization styles range from shear dilation to compaction bands. In this study, we conduct finite element modeling of constitutive behaviors of rocks retrieved from the tight glutenite reservoir formation using a thermodynamic-consistent plasticity model. The shear dilation to compaction transition is well characterized. Poromechanical analysis is also conducted to analyze the plastic zone development around a borehole drilled in an over pressured reservoir. The simulated stress-paths of key points around the borehole are used to demonstrate the plastic strain development processes. The impact of in-situ stress on the wellbore stability is highlighted, and a comparison with the results from using the traditional plastic constitutive model is conducted.

Optimized design of wide band polarization diversified compact microstrip transponder antenna for satellite communication

AbstractA major limitation of microstrip antenna is its narrow impedance bandwidth (1%–5%) which makes it unsuitable for the operation over C band, used for various satellite communications, Wi‐Fi devices, some surveillance, and weather radar systems. Furthermore, increasing bandwidth (BW) can cause a reduction in radiation efficiency and antenna gain making it unsuitable for some particular applications. Nonplanar and defected ground structures may provide enhanced BW but it also creates distorted radiation pattern, unwanted loss of power, and mechanical mounting hazard. Polarization diversity also gives flexibility in use for various applications. A unique compact dual band and Ultra‐Wide Band (viz., 4.29–5.32 and 6.04–8.77 GHz) and polarization diversified (viz., circular and dual polarization) perturbed square microstrip patch antenna has been proposed here overcome the above shortcomings. Innovative corner parasitic loading and shorting via implementation ensures the fulfillment of the above features with improved 24.45% and 33.75% BW.

Analytical Quality by Design (AQBD) Assisted Development and Validation of HPTLC Method for Estimation of Rottlerin in Topical Patch Formulation

Pharmacognosy Research,2023,15,2,267-276.DOI:10.5530/pres.15.2.029Published:February 2023Type:Original Article Authors:Kaumudee Bodas, Vaibhav M Shinde, Deshmukh Vishal, and Deshmukh Sheetal Author(s) affiliations:Kaumudee Bodas1, Vaibhav M Shinde1,*, Deshmukh Vishal2, Deshmukh Sheetal2 1Centre for Advanced Research in Pharmaceutical Sciences, Poona College of Pharmacy, Pune, Maharashtra, INDIA. 2Bharati Vidyapeeth (Deemed to be University), Yashwantrao Mohite Institute of Management, Karad, Maharashtra, INDIA. Abstract:Background: Rottlerin, a natural polyphenolic ketone is a major constituent of Mallotus philippensis (Lam.) Mull. Arg. plant. Although, less explored it has diverse array of therapeutic applications. Objectives: The current work aimed to develop novel, simple, speedy, accurate, potent High Performance Thin Layer Chromatography Method (HPTLC) to separate, and quantify rottlerin from the herbal topical patch In-House formulation. Materials and Methods: This was the foremost attempt to develop and validate HPTLC method using Analytical Quality by design (AQbD) approach. Box Behnken design (BBD) coupled with response surface methodology approach was followed for the systematic optimization. The end results of toluene content, chamber conditioning time, and solvent front on Rf value of rottlerin was studied. The optimised method was validated as per ICH guidelines. Results: For HPTLC, stationary phase used was aluminium plates 60F254 coated with silica gel as. AQbD optimised conditions were mobile phase proportion namely toluene: ethyl acetate: methanol: ammonia (5:4:2:0.2), development distance 80 mm, band width 6mm, and chamber saturation time 10 min. The method generated well resolved and compact bands at Rf of 0.41±0.05. The developed method exhibited high accuracy, precision, robustness, and recovery. The quantity of Rottlerin in developed herbal patch was found to be 134.8 ng/band. Conclusion: In a nutshell, the present study undeniably vouches for a QbD based method development approach for Rottlerin and can be extrapolated to estimate it in other herbal extracts, or marketed formulations Keywords:Analytical Quality by design (AQbD), HPTLC, Mallotus philippensis (Lam.) Mull. Arg., Rottlerin, Topical patch.View:PDF (1.15 MB)

Design of double-notch UWB filter with upper stopband characteristics based on ACPW-DGS.

In this manuscript, a compact (size only 9.8mm*9.8mm) Ultra Wide Band (UWB) bandpass filter with a new structure is proposed, which can be used in the UWB wireless communication band authorized by the FCC. The top plane is composed of a pair of back-to-back microstrip lines, and the ground plane structure is based on an asymmetric coplanar waveguide-defect ground structure (ACPW-DGS). UWB is formed by the vertical electromagnetic coupling of the top plane and the ground plane. On this basis, split ring resonator (SRR) and C type resonator (CTR) are utilized to place double notch bands. A novel third order nested C-type resonator (TONCTR) is obtained by performing CTR, which can further optimize the upper stopband while ensuring double notch bands. The filter can be used for filtering within the UWB system, and it can also avoid the amateur radio band (9.2 -10.3GHz) and the X-band satellite link band (9.6-12.3GHz) on UWB communication systems. Finally, the measured results from the fabricated prototype are basically consistent with the simulation results.

Dynamic strain localization into a compaction band via a phase-field approach

We present a new phase-field formulation for the formation and propagation of a compaction band in high-porosity rocks. Novel features of the proposed formulation include (a) the effects of inertia on the rate of development of compaction bands, and (b) degradation mechanisms in tension, compression, and shear appropriate for dynamic strain localization problems where disturbances propagate in time in a wave-like fashion to induce micro-cracking, grain crushing, and frictional grain rearrangement in the rock. We also present a robust numerical technique to handle the spatiotemporal formation and evolution of the compaction band. We validate the model by simulating a benchmark problem involving a V-shape notched cylindrical specimen of Bentheim sandstone tested in conventional triaxial compression. The model is shown to reproduce different geometric styles of deformation that include pure compaction, shear-enhanced compaction, and a combination of pure and shear-enhanced compaction, where the combination mechanism consists of a straight primary compaction band surrounded by secondary chevron bands.

A compact 5G band N77 bandpass filter with multiple zeros based on GaAs integrated passive device process

AbstractIn this paper, a compact 5G band N77 bandpass filter (BPF) with multiple zeros is designed based on GaAs integrated passive device (IPD) process. The BPF consists of lumped capacitors and inductors. Hybrid resonator technology which consists of a combination of shunt and series resonant tanks are proposed to produce six transmission zeros in the stopband and significantly improve the filter selectivity. In addition, a series resonator at the output port of the filter was introduced to produce another transmission zero at the upper stopband and further improve the stopband suppression. Meanwhile, to reduce the area and insertion loss of the filter, a stacked inductor is designed by using IPD technology, which can greatly reduce the area and size of the filter. The minimum insertion loss is 1.782 dB. The size of the entire BPF is 1.3 mm × 0.7 mm.

Compact 5G Vivaldi Tapered Slot Filtering Antenna with Enhanced Bandwidth

Compact fifth-generation (5G) low-frequency band filtering antennas (filtennas) with stable directive radiation patterns, improved bandwidth (BW), and gain are designed, fabricated, and tested in this research. The proposed filtennas are achieved by combining the predesigned compact 5G (5.975 – 7.125 GHz) third-order uniform and non-uniform transmission line hairpin bandpass filters (UTL and NTL HPBFs) with the compact ultrawide band Vivaldi tapered slot antenna (UWB VTSA) in one module. The objective of this integration is to enhance the performance of 5.975 – 7.125 GHz filtennas which will be suitable for modern mobile communication applications by exploiting the benefits of UWB VTSA. Based on NTL HPBF, more space is provided to add the direct current (DC) biassing circuits in cognitive radio networks (CRNs) for frequency reconfigurable applications. To overcome the mismatch between HPBFs and VTSA, detailed parametric studies are presented. Computer simulation technology (CST) software is used for the simulation in this study. Good measured S11 appeared to be < −13 and < −10.54 dB at 5.48 – 7.73 and 5.9 – 7.98 GHz with peak realized gains of 6.37 and 6.27 dBi, for VTSA with UTL and NTL HPBFs, respectively which outperforms the predesigned filters. Validation is carried out by comparing the measured and simulated results.

A compact triple bands C shaped multiband monopole antenna for WLAN and WiMAX application

Antennas play a crucial role in communication as they serve as both transmitters and receivers. They are capable of supporting numerous applications and demanding higher bandwidth among which monopole antennas have emerged as a superior alternative to traditional antennas. A novel coplanar waveguide (CPW)-fed triple-band monopole antenna is proposed for WLAN and WiMAX applications. The antenna features a compact and simple Cshaped strip structure, allowing for easy fabrication. The prototype exhibits triple operating bands covering the required bandwidths of 2.4/5.2/5.8 GHz WLAN and 3.5/5.5 GHz WiMAX standards. Good radiation performance and antenna gain are achieved across the three frequency ranges. Another compact monopole multiband antenna is designed, consisting of five rectangular patches forming a C-shaped structure. It operates at frequencies covering WiMAX, WLAN, short-range radar, and wireless data transmission applications. The antenna demonstrates significant bandwidth to accommodate the respective frequency ranges required for these applications. The antenna design is simulated using HFSS v13 software.

A compact dual band T-shaped monopole antenna for WLAN and C-band application

The design of a compact monopole dual-band antenna suitable for dual-band applications is proposed in this research. The antenna consists of eight rectangular patches, each measuring 40 × 30 × 1.6 mm³. It is designed to operate in two frequency bands: 2.18–2.63 GHz and 7.10–7.91 GHz, with resonance frequencies at 2.4 GHz and 7.5 GHz, ensuring a return loss (S11) of less than 10 dB. The results demonstrate that the proposed antenna achieves a bandwidth of 450 MHz (2.18–2.63 GHz) and 810 MHz (7.10–7.91 GHz). This bandwidth coverage allows for the inclusion of the 2.4 GHz range required for WiMAX as well as the 7.5 GHz range suitable for short-range radar and wireless data transmission applications. The antenna is simulated using HFSS v13 software, providing an accurate and reliable analysis of its performance. The compact size of the antenna makes it suitable for integration into various wireless devices and systems, offering versatility and adaptability. Overall, the presented compact monopole dual-band antenna demonstrates its efficacy in achieving dual-band operation, covering essential frequency ranges for WiMAX, short-range radar, and wireless data transmission applications. Its compact design and wide bandwidth make it a valuable candidate for modern wireless communication systems.