Green synthesis of silver nanoparticles using Nervalia zeylanica leaf extract and evaluation of their antioxidant,catalytic, and antimicrobial potentials

ABSTRACT

Here we report a simple, one-pot, inexpensive, and eco-friendly method for the synthesis of silver nanoparticles. The leaf extract of a medicinal plant Nervalia zeylanica was used as reducing and stabilizing agent for the synthesis of nanoparticles by microwave-assisted strategy. The nanoparticles show characteristic surface plasmon peak at 468?nm in UV–vis absorption spectrum. The involvement of phytochemicals in the reduction and stabilization of nanoparticles was confirmed by FTIR analysis. Using X-ray diffraction analysis, the crystalline nature of the nanoparticles was demonstrated. Transmission electron microscopic analysis shows that the nanoparticles were in spherical shape with average particle size of 34.2?nm. The antioxidant studies were performed by the 1,1-diphenyl-2-picryl hydrazyl method. The nanoparticles show excellent scavenging activities than the leaf extract. The IC₅₀ values of silver nanoparticles and the leaf extract, respectively, were 15.20 and 92.83?µg?mL^?1. The catalytic activities of synthesized nanoparticles were examined by using them in the reduction of organic dyes. The nanoparticles show excellent catalytic activities and follow pseudo-first-order kinetics. The antimicrobial activities of nanoparticles were analyzed by an agar well diffusion method against six microbial strains and found that the nanoparticles were highly toxic against all the tested microbial strains.     

Two-photon-assisted excited state absorption in nanocomposite films of PbS stabilized in a synthetic glue matrix

Strong nonlinear absorption is observed in nanocomposite films containing PbS nanocrystals of mean size of 3.3?nm stabilized in a commercial poly(vinyl acetate) glue by a novel and simple chemical route of synthesis. A significant blueshift of the optical absorption edge indicates strong quantum confinement. The mean nanocrystal size was characterized by x-ray diffraction and transmission electron microscopy. The surface structure of nanocrystals is analysed using infrared spectroscopy. The excitonic transitions are probed by photoacoustic spectroscopy and the results are analysed on the basis of theoretical calculations using envelope function formalism. Results of open aperture z-scan experiments suggest a model involving saturable absorption followed by two-photon absorption at a lower concentration while the data for a higher concentration fitted saturable absorption followed by three-photon absorption. Free carrier absorption due to two-photon-assisted excited state absorption appears to be the predominant mechanism of optical nonlinearity.     

Metrics for measuring the consistencies of requirements with objectives and constraints

Requirements engineering (RE) is essential to succeed in software projects. That is, it is important to elicit sound requirements for proper performing of RE. If some requirements are inconsistent with a given objectives and constraints, these requirements may hinder the performance of RE. For this reason, it is necessary to pre-check the consistency of requirements. We propose the metrics for evaluating requirements by considering given objectives and constraints. Our metrics are validated by two sample scenarios: “Payroll and Roster Planning of Hospital” and “Noise Source Location System.” At the result, we expect that these metrics would be helpful when selecting a set of consistent requirements.     

A knowledge-based framework for extracting components in agile systems development

Considerable strides have been made in the use of components in software development. Many proprietary enterprise resource planning (ERP) software environments use modular components to develop and customize “best practices” to meet a specific organizational need. In agile application development, many developers and users are asked to design systems in a short period of time. These applications may use components that are embedded in software repositories. The challenge then is how to select the right software components (data and procedures) to meet an application requirement. Although experienced developers may select and customize components to meet the needs of an application, such expertise may not be available to other applications. This paper presents a knowledge-based framework to select and customize software components and demonstrates its value in deriving quality specifications, even when the developers are relatively inexperienced.     

Web personalization for user acceptance of technology: An empirical investigation of E-government services

E-Commerce firms have adopted Web Personalization techniques extensively in the form of recommender systems for influencing user behavior for customer retention. Although there are numerous studies in this area, academic research addressing the role of Web Personalization in user acceptance of technology is very scant. Further, owing to the potential of recommender systems to attract and retain customers, most studies in web personalization have been done in E-Commerce setting. In this research, the ‘Consumer Acceptance and Use of Information Technology’ theory proposed in previous research has been extended to include web personalization as a moderator and has been tested in an E-Government context. Data collection involved conducting a laboratory experiment with the treatment group receiving personalized web forms for requesting an E-Government service. Our analyses show that personalizing the Web by self-reference and content relevance has a significant moderator role in influencing the relationship between determinants of intention to use and behavioral intention in certain cases.     

A knowledge-based system for improving the consistency between object models and use case narratives

In today’s systems development environments, object models are playing an increasingly important role in contributing to the agility and flexibility expected of the information systems being built. While current computer-aided software engineering tools can aid in creating object models, they do not provide much support in ensuring that the object models created are consistent with the specifications in use case narratives. This paper presents a methodology and a knowledge-based system to facilitate the verification of consistency of a given object model against a set of use case narratives. The methodology is implemented as a prototype knowledge-based extension to an open source CASE tool. The prototype’s ability to reliably extract relevant information from use case narratives and its role in verifying the consistency of object models have been evaluated using a laboratory experiment. By analyzing use case narratives utilizing natural language processing techniques and applying collaboration patterns and heuristics, this methodology can determine missing and invalid model elements to guide the analyst in creating object models that are consistent with the requirements specified in a set of use case narratives. The results from this design science research indicate that the prototype system can be a useful tool to assist in this process.     

Ag-polyaniline nanocomposite cladded planar optical waveguide based humidity sensor

The paper reports synthesis of Ag-polyaniline nanocomposite and its evaluation as an active optical cladding on a planar optical waveguide (POW) as a humidity sensor with variable concentration of the composite. The nanocomposite is dispersed in acetonitrile, and spin coated on the planar waveguide to form a clad. The system shows response to humidity, when tested in the range of 20–92% relative humidity (RH). A prism film coupling is used to characterize the cladded waveguide. The maximum sensitivity is seen for 47% concentration of the nanocomposite in acetonitrile. The response and recovery of the sensor are 8 and 55 s respectively. The low hysteresis is exhibited by the sensor. The sensor has repeatability and reproducibility. Material characterization is done using Scanning Electron Micrograph (SEM), X-Ray Diffraction (XRD), Ultraviolet Spectroscopy (UV) and Fourier Transform Infrared Spectroscopy (FTIR).     

Hidden Two-Stream Collaborative Learning Network for Action Recognition

The two-stream convolutional neural network exhibits excellent performance in the video action recognition. The crux of the matter is to use the frames already clipped by the videos and the optical flow images pre-extracted by the frames, to train a model each, and to finally integrate the outputs of the two models. Nevertheless, the reliance on the pre-extraction of the optical flow impedes the efficiency of action recognition, and the temporal and the spatial streams are just simply fused at the ends, with one stream failing and the other stream succeeding. We propose a novel hidden twostream collaborative (HTSC) learning network that masks the steps of extracting the optical flow in the network and greatly speeds up the action recognition. Based on the two-stream method, the two-stream collaborative learning model captures the interaction of the temporal and spatial features to greatly enhance the accuracy of recognition. Our proposed method is highly capable of achieving the balance of efficiency and precision on large-scale video action recognition datasets.     

Testing in Industrial Experiments With Ordered Categorical Data

This article deals with some techniques for analyzing ordered categorical data from industrial experiments for quality improvement. Taguchi's accumulation analysis method is shown to have reasonable power fordetecting important location effects; however, it is an unnecessarily complicated procedure. For detecting dispersion effects, it need not even be as powerful as Pearson's chi-squared test. Instead two simple and easy to use scoring schemes are suggested for identifying the location and dispersion effects separately. The techniques are illustrated on data from an experiment to optimize the process of forming contact windows in complementary metal-oxide semiconductor circuits.