Structural,thermal, dielectric,nonlinear optical properties and DFT investigations of a novel material 2-(6-chloropyridin-3-yl)-N'-(2,3-dihydro-1,4-benzodioxin-6-ylmethylidene)acetohydrazide for optoelectronic applications

A new organic nonlinear optical (NLO) material 2-(6-chloropyridin-3-yl)-N'-(2,3-dihydro-1,4-benzodioxin-6-ylmethylidene)acetohydrazide (CDA) has been synthesized by reflux method. Single crystals were grown by slow evaporation technique and the crystal structure was elucidated by single crystal X-ray diffraction method. Density functional theory (DFT) calculations at B3LYP/6–31+?+?G(d, p) basis set was used to predict the molecular geometry and were carried out further to comprehend the electronic structure, vibrational spectra, natural bonding orbitals (NBO), frontier molecular orbitals (FMO) and molecular electrostatic potential (MEP). An optical transparency at the cut-off wavelength of 355 nm was determined by UV–Vis–NIR spectroscopy. Thermal behavior of CDA was studied by TGA/DTA analysis. The dielectric constant (ε), dielectric loss (tan δ) and AC conductivity as a function of frequency and temperature was studied. Second Harmonic Generation (SHG) efficiency of the CDA was determined using Kurtz and Perry powder technique and was 0.5 times greater than that of the KDP crystal. The third-order nonlinear optical properties were investigated in solution by Z-scan technique using a continuous wave (CW) DPSS laser at the wavelength of 532 nm. The title compound exhibited significant two-photon absorption (β?=?2.228?×?10–4 cm W^?1), nonlinear refraction (n₂?=?1.095?×?10–8 cm² W^?1) and optical limiting (OL threshold?=?2.511?×?103 W cm^?2) under the CW regime. The nonlinear optical parameters were calculated using time-dependent Hartree–Fock (TDHF) method. The overall obtained results suggested that the studied CDA molecule could be a potential NLO material for frequency generator, optical limiters and optical switching applications.

     

Effect of Thermomechanical Treatment on X-Ray Elastic Constants and Residual Stresses in HSLA-100 Steel

The thermomechanical treatment of HSLA-100 steel is undertaken to upgrade its properties. The plastic deformation in our study was done below and above the recrystallization temperature of austenite, as well in the two-phase ( + ) region, followed by accelerated cooling. The plates were subsequently aged at two temperatures. The optical microstructures and hardness were done, and the effect of finish rolling temperature was established. The residual stress, X-ray elastic constants (XEC) and relative peak intensity were determined using X-ray diffraction. The effect of aging temperature on hardness, residual stress, Young's modulus, and Poisson's ratio was established. The residual stress values calculated using the XEC values obtained were found to be on the lower side compared to stress values using bulk elastic constants. The maximum difference in stress values is about 27%, which justifies the determination and use of XEC to obtain absolute values of stress.     

Ferroelectrics as Smart Mechanical Materials

The mechanical properties of materials are insensitive to space inversion, even when they are crystallographically asymmetric. In practice, this means that turning a piezoelectric crystal upside down or switching the polarization of a ferroelectric should not change its mechanical response. Strain gradients, however, introduce an additional source of asymmetry that has mechanical consequences. Using nanoindentation and contact‐resonance force microscopy, this study demonstrates that the mechanical response to indentation of a uniaxial ferroelectric (LiNbO₃) does change when its polarity is switched, and use this mechanical asymmetry both to quantify its flexoelectricity and to mechanically read the sign of its ferroelectric domains.     

Characterization of phyto-nanoparticles from Ficus krishnae for their antibacterial and anticancer activities

Background: Ovarian cancer is deadliest of fifth leading cause of death in women worldwide. This is due to advanced-stage disease rate associated with the development of chemoresistance. Hence, the current study emphasizes the process of synthesis of silver nanoparticles (AgNPs) from green chemistry method. Ficus krishnae is a perennial plant, native to India, used in folklore medicine to treat various diseases.

Objective: For the development of reliable, ecofriendly, less expensive process for the synthesis of AgNPs against bacterial and ovarian cancer.

Methodology: The synthesis of silver nanoparticles from stem bark of Ficus krishnae was carried out. The synthesized nanoparticles are subjected by UV-Vis spectrophotometer, scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and FTIR analysis. The antibacterial efficacy also determined by disc diffusion method, MIC, CFU and growth curve. In vitro cytotoxicity effect of aqueous extract and AgFK nanoparticle in ovarian cancer cell line by MTT assay was performed.

Results: The formation of AgNPs was confirmed by UV-VIS spectroscopic absorbance shown that peak at 435?nm. XRD photograph has indicated the face-centered cubic structure of the synthesized AgNPs. SEM study demonstrated that the size from 160 to 260?nm with interparticle distance, whereas shape is spherical. The particle size were ranging from 15 to 28?nm determined by XRD pattern. The antibacterial and cytotoxicity activity of this nanoparticle has showed a potential activity when compared with standards.

Conclusion: The present study confirms that the biosynthesized AgNPs from Ficus krishnae stem bark extract have a great affiance as antibacterial and anticancer agent.     

An agent-based recommender system for developing customized families of products

Electronic markets and web-based content have improved traditional product development processes by increasing the participation of customers and applying various recommender systems to satisfy individual customer needs. Agent-based systems based on agents’ roles and tasks can provide appropriate tools to solve product design problems by recommending design knowledge and information. This paper introduces an agent-based recommender system to support designing families of products based on customers’ preferences in dynamic electronic market environments. In the proposed system, a market-based learning mechanism is applied to determine the customers’ preferences for recommending appropriate products to customers of the product family. We demonstrate the implementation of the proposed recommender system using a multi-agent framework. Through simulated experiments, we illustrate that the proposed recommender system can help determine the preference values of products for customized recommendation and market segment design in various electronic market environments.     

Keyswitch orientation can reduce finger joint torques during tapping on a computer keyswitch

OBJECTIVE: To examine the effects of keyswitch orientation on joint torques. BACKGROUND: The fingertip produces primarily vertical forces during single-finger tapping on a computer keyswitch. However, horizontal force components within the sagittal plane of the finger could reduce net joint torques. METHOD: Eleven participants tapped on a keyswitch oriented in three directions: vertical, tilted 30 degrees such that when pressed it moved away from the user (similar to a positive-tilt keyboard), and tilted 30 degrees such that when pressed it moved toward the user (similar to a negative-tilt keyboard). Participants also tapped on a prototype cantilever keyswitch design in which the key cap moves along the arc of a bending beam gradually away from the user. Miniature electro-optical goniometers measured the finger posture, and a two-axis force sensor measured fingertip forces. RESULTS: Tapping on a keyswitch oriented such that it moves away from the user when pressed reduced net joint torques by 47% relative to tapping on a vertically orientated keyswitch and by 56% relative to tapping on a keyswitch oriented toward the user, whereas the cantilever design resulted in 14% decreases in net joint torque relative to the vertical orientation. CONCLUSION: Reductions of torques resulted from decreasing the moment arm of the fingertip force about the joints. APPLICATION: Keyboard design should incorporate keyswitch mechanism angles along with other postural and geometric constraints to reduce exposure of the finger joints and muscles to force during typing.     

Analysis and Experiment of Self-Powered,Pulse-Based Energy Harvester Using 400 V FEP-Based Segmented Triboelectric Nanogenerators and 98.2% Tracking Efficient Power Management IC for Multi-Functional IoT Applications

A self-powered system for the Internet of Things (IoT) is demonstrated for efficient energy harvesting of naturally available mechanical energy. In this system, new contact-separation mode triboelectric nanogenerators (TENGs), based on fluorinated ethylene propylene, are investigated using the segmented multi-TENG configuration to reduce the effect of parasitic capacitance. The TENG extraction is optimized using a unit step excitation involved with the Dawson function to achieve a high voltage (400 V) and a high current (26.6 µA). To fully extract the power of the TENGs, the power management integrated circuit (PMIC) specially designed for adaptively controlled, high-voltage (HV) maximum power point tracking (MPPT) is proposed. The PMIC implemented in a bipolar CMOS-DMOS 180 nm process can handle a wide input range (5–70 V) by consuming 420 nW. The MPPT control allows a wide range of impedance matching from 10 to 300 MΩ, achieving a tracking efficiency of up to 98.2%. The end-to-end efficiency of 88% demonstrates state-of-the-art performance. To supply a higher instantaneous power than that available from the TENGs, a duty-cycling technique is successfully demonstrated. The proposed energy harvesting system provides a promising approach to realizing sustainable and autonomous energy sources for various IoT applications.     

Use of geographical information system and remote sensing techniques for planning culture‐based fisheries in non‐perennial reservoirs of Sri Lanka

The presence of a wide areal extent of small‐sized village reservoirs offers a considerable potential for the development of culture‐based fisheries (CBFs) in Sri Lanka. To this end, this study uses geographical information systems (GISs) and remote sensing (RS) techniques to determine the morphometric and biological characteristics most useful for classifying non‐perennial reservoirs for CBF development and for assessing the influence of catchment land‐use patterns on potential CBF yields. The reservoir shorelines at full water supply level were mapped with a Global Positioning System to determine shoreline length and reservoir areal extent. The ratio of shoreline length to reservoir extent, which was reported to be a powerful predictor variable of CBF yields, could be reliably quantified using RS techniques. The areal extent of reservoirs, quantified with RS techniques (RS extent), was used to estimate the ratio of forest cover plus scrubland cover to RS extent and was found to be significantly related to the CBF yield (R² = 0.400; P < 0.05). The results of this study indicated that morphometric characteristics and catchment land‐use patterns, which might be viewed as indices of biological productivity, can be quantified using RS and GIS techniques.     

Analysis of reflectance spectra of tropical seagrass species and their value for mapping using multispectral satellite images

ABSTRACT

Mapping of the distribution of individual seagrass species is essential for any attempts to manage seagrass ecosystems. It is therefore important to understand how the spectra of different seagrass species vary, in order to establish their unique absorption features and how these can be utilised for mapping by making use of remote-sensing images. This paper presents measurements of the reflectance spectra between 400 and 900 nm for nine tropical species of seagrass. Continuum removal and multispectral resampling procedures were applied to the spectra. Dendrogram analysis was carried out to identify species clustering as the basis for a mapping scheme. Spectral Angle Mapper (SAM) and Spectral Information Divergence (SID) approaches were employed for the classification of seagrass species using WorldView-2 images and measured spectra as the input endmember. Classification Tree Analysis (CTA) and an image segmentation approach using CTA (Object-Based Image Analysis – OBIA) were performed as a means of comparison. The results indicate that the absorption features and overall shape of the spectra for all seagrass species are relatively similar, and implied that the major differences are attributable to the absolute reflectance values. Consequently, SAM and SID produced results of low accuracy (<30%), whereas, CTA and OBIA delivered results exhibiting higher accuracy (60–92%). The use of a spectral-based classification algorithm was ineffective for the classification and mapping of seagrass species using multispectral images. The utilisation of absolute reflectance values was beneficial for the classification of seagrass species having similar spectral shape.