Study of pure and l-tartaric acid doped ammonium dihydrogen phosphate single crystals: A novel nonlinear optical non-centrosymmetric crystal

Single crystals of pure and l-tartaric acid (LTA) C₄H₆O₆ doped ammonium dihydrogen phosphate (ADP) (NH₄) H₂PO₄ were grown by slow evaporation solution technique (SEST) at ambient conditions. Powder X-ray diffraction (PXRD) analysis was carried out to confirm the crystal structure and no additional phase was observed due to doping except a systematic variation in peak intensities. Fourier transform infrared spectral analysis was done to examine the presence of various functional groups in the grown crystals. UV–VIS–NIR spectroscopic analysis was carried out to see the change in optical transparency of pure ADP and crystals due to LTA with different doping concentrations. Second harmonic generation (SHG) efficiency measurement was done to examine the enhancement in the nonlinear optical characteristics of the grown crystals. The effect of LTA dopant on crystal morphology, thermal and mechanical properties of ADP have also been presented in this paper. The above studies reveal the effect of incorporation of LTA into the lattice of ADP crystals.     

Ce-substituted Lithium Ferrite:Preparation and Electrical Relaxation Studies

Ce-substituted lithium ferrite,Li_(0.5)Ce_xFe_(2.5-x)O_4(x = 0,0.05 and 0.1) compositions were synthesized from metal nitrates and citric acid by the solution combustion process by keeping the oxidizer to fuel ratio at unity.The thermal decomposition process was investigated by thermogravimetry—differential thermal analysis,which showed a stable phase formation above 600 C.The phase composition and molecular bonding of Li_(0.5)Ce_xFe_(2.5-x)O_4 were characterized by X-ray powder diffraction analysis and Fourier transform infrared spectroscopy,respectively.An extensive study of electrical relaxation process has been represented with impedance and modulus as a function of frequency at different temperatures.The activation energy obtained from both the formalisms was found to be equal within the error.The dc conductivity and hopping frequency were thermally activated and their activation energies were found to be in the range of 0.69-0.64 eV for x = 0.05.The scaling of modulus and impedance were used to understand the electrical relaxation behaviour of the compositions and they suggest the time temperature superposition principle.     

Experimental Verification of Photovoltaic-based Three-phase Four-wire Series Hybrid Active Power Filter

Abstract—This article proposes a photovoltaic and battery interfaced series hybrid active power filter, which is comprised of a series active power filter and an inductor-capacitor (LC) shunt passive filter. The main benefits of the proposed system provide the compensation against the voltage harmonics, current harmonics, and voltage interruption for the whole day. A series active power filter demands a source of energy for compensating the voltage sag/swell. The proposed topology utilizes the green energy source with an energy storage unit to meet the DC-link voltage requirement of the series active power filter. The control strategy is based on the dual formulation of the compensation system principles with adaptive fuzzy logic controller. The simulation and experimental studies are carried out to validate the effectiveness of the proposed photovoltaic interfaced three-phase four-wire series hybrid active power filter.     

Quantification of extreme thermal gradients during in situ transmission electron microscope heating experiments

Studies on materials affected by large thermal gradients and rapid thermal cycling are an area of increasing interest, driving the need for real time observations of microstructural evoultion under transient thermal conditions. However, current in situ transmission electron microscope (TEM) heating stages introduce uniform temperature distributions across the material during heating experiments. Here, a methodology is described to generate thermal gradients across a TEM specimen by modifying a commercially available MEMS-based heating stage. It was found that a specimen placed next to the metallic heater, over a window, cut by FIB milling, does not disrupt the overall thermal stability of the device. Infrared thermal imaging (IRTI) experiments were performed on unmodified and modified heating devices, to measure thermal gradients across the device. The mean temperature measured within the central viewing area of the unmodified device was 3–5% lower than the setpoint temperature. Using IRTI data, at setpoint temperatures ranging from 900 to 1,300°C, thermal gradients at the edge of the modified window were calculated to be in the range of 0.6 × 10⁶ to 7.0 × 10⁶°C/m. Additionally, the Ag nanocube sublimation approach was used, to measure the local temperature across a FIB-cut Si lamella at high spatial resolution inside the TEM, and demonstrate “proof of concept” of the modified MEMS device. The thermal gradient across the Si lamella, measured using the latter approach was found to be 6.3 × 10⁶°C/m, at a setpoint temperature of 1,000°C. Finally, the applicability of this approach and choice of experimental parameters are critically discussed.     

Antibacterial labdane diterpenoids of Ulva fasciata Delile from southwestern coast of the Indian Peninsula

Chromatographic purification of the dichloromethane-soluble fraction of alga, on neutral alumina, using increasing concentrations of ethylacetate/n-hexane as eluents, yielded seven labdane diterpenoids (1–7) as major constituents of green alga Ulva fasciata. Structures of these diterpenoids were established using extensive spectroscopic techniques. Antimicrobial assay showed that the compounds labda-14-ene-3α,8α-diol (2) and labda-14-ene-8α-hydroxy-3-one (4) were inhibitory to the growth of Vibrio parahaemolyticus and Vibrio alginolyticus with minimum inhibitory concentrations of 30 μg/ml by 2, and 40 μg/ml by 4, respectively against the former and 30 μg/ml by 2, and 80 μg/ml by 4, respectively, against the latter. Structure–activity relationship analyses revealed that the compounds with electronegative hydroxyl or carbonyl group(s) exhibit greater activities, apparently by proton exchange reaction with the basic aminoacyl residue at the macromolecular receptor site of virulent enzymes of pathogenic bacteria. These might provide promising therapeutic agents against infections with multi-resistant Gram-negative fish pathogenic bacteria.     

Properties of Natural Fibers Separated from Chromolaena odorata and Mikania micrantha

This paper reports the possibility of separating natural fibers from two invasive alien plants Chromolaena odorata and Mikania micrantha. These two are considered as high-risk species on the basis their invasiveness and being a menace to the natural biodiversity of Kerala, India. Water retting and alkali extraction methods were used for the separation of stem fibers. Fibers obtained showed similar properties to currently used common fibers. Based on morphometric measurements and derived values, such as slenderness ratio, flexibility ratio, and Runkel ratio, these fibers are expected to be suitable for industrial purposes.     

A machine learning assisted optical multistage interconnection network: Performance analysis and hardware demonstration

Integration of the machine learning (ML) technique in all-optical networks can enhance the effectiveness of resource utilization, quality of service assurances, and scalability in optical networks. All-optical multistage interconnection networks (MINs) are implicitly designed to withstand the increasing high-volume traffic demands at data centers. However, the contention resolution mechanism in MINs becomes a bottleneck in handling such data traffic. In this paper, a select list of ML algorithms replaces the traditional electronic signal processing methods used to resolve contention in MIN. The suitability of these algorithms in improving the performance of the entire network is assessed in terms of injection rate, average latency, and latency distribution. Our findings showed that the ML module is recommended for improving the performance of the network. The improved performance and traffic grooming capabilities of the module are also validated by using a hardware testbed.     

Tricube Weighted Linear Regression and Interquartile for Cloud Infrastructural Resource Optimization

Cloud infrastructural resource optimization is the process of precisely selecting the allocating the correct resources either to a workload or application. When workload execution, accuracy, and cost are accurately stabilized in opposition to the best possible framework in real-time, efficiency is attained. In addition, every workload or application required for the framework is characteristic and these essentials change over time. But, the existing method was failed to ensure the high Quality of Service (QoS). In order to address this issue, a Tricube Weighted Linear Regression-based Inter Quartile (TWLR-IQ) for Cloud Infrastructural Resource Optimization is introduced. A Tricube Weighted Linear Regression is presented in the proposed method to estimate the resources (i.e., CPU, RAM, and network bandwidth utilization) based on the usage history in each cloud server. Then, Inter Quartile Range is applied to efficiently predict the overload hosts for ensuring a smooth migration. Experimental results show that our proposed method is better than the approach in Cloudsim under various performance metrics. The results clearly showed that the proposed method can reduce the energy consumption and provide a high level of commitment with ensuring the minimum number of Virtual Machine (VM) Migrations as compared to the state-of-the-art methods.     

Impact of loss functions on semantic segmentation in far-field monitoring

Although previous research laid the foundation for vision-based monitoring systems using convolutional neural networks (CNNs), too little attention has been paid to the challenges associated with data imbalance and varying object sizes in far-field monitoring. To fill the knowledge gap, this paper investigates various loss functions to design a customized loss function to address the challenges. Scaffold installation operations recorded by camcorders were selected as the subject of analysis in a far-field surveillance setting. It was confirmed that the data imbalance between the workers, hardhats, harnesses, straps, and hooks caused poor performances especially for small size objects. This problem was mitigated by employing a region-based loss and Focal loss terms in the loss function of segmentation models. The findings illustrate the importance of the loss function design in improving performance of CNN models for far-field construction site monitoring.     

A Review on the Application-Focused Assessment of Plasma Electrolytic Oxidation (PEO) Coatings Using Electrochemical Impedance Spectroscopy

The plasma electrolytic oxidation (PEO) coatings have different applications, and their modifications or developments are generally with a specific application target. Therefore, the PEO coating assessments often envisage that particular application without considering other possibilities or infeasibilities of developed PEO coatings from a different perspective. Electrochemical impedance spectroscopy (EIS), a powerful technique for PEO coating assessment, is manifold because it can assess almost every structural, morphological, chemical, and electrochemical feature of PEO coatings. Therefore, a review paper describing an all-purpose EIS behavior of PEO coatings is essential for researchers and engineers for a complete PEO coating assessment beyond their target application. Herein, the relevant PEO coating literature reports sufficient to understand the PEO coating assessment fundamentals are included in this review for researchers and engineers from all perspectives without compiling all literature reports on EIS studies of PEO coatings.