Circulation rates of boiling liquids in a vertical tube

An experimental study of heat transfer to boiling liquids under natural convective flow has been carried out in a single tube vertical thermosiphon reboiler to investigate the effect of heat flux and submergence on circulation rates. The test liquids used were distilled water, various concentrations of propan-2-ol in water and their azeotrope. The test section was an electrically heated stainless steel tube of 25.56 mm i.d., 28.85 mm o.d. and 1900 mm long with twenty-one spot welded copper constantan thermocouples to measure the variations in wall temperature along its axis. The uniform heat fluxes in the range of 3.5–42.4 kW/m² were employed while inlet liquid sub-cooling varied from 0.2 to 30.7 °C. The liquid submergence levels were maintained in the range 30–100%. The typical experimental data has been graphically presented and discussed. An empirical correlation has been developed from the experimental data of the present study through regression analysis.     

A new technique for the construction of confusion component based on inverse LA-semigroups and its application in steganography

The present article introduced a novel idea for information hiding namely steganography. We have used new notions for the construction of the nonlinear component for block cipher based on inverse LA-semigroups. This nonlinear component fundamentally provides confidentiality in the proposed steganographic algorithm. The construction of the algorithm is fundamentally twofold. Firstly, we have constructed a novel scheme to design confusion component namely substitution box (S-box). Secondly, we have utilized the anticipated nonlinear component in digital steganography. The suggested algorithm is tested for different standard digital images. The authentication of the proposed algorithm is confirmed through statistical analysis.

     

Biosynthesis and characterisation of nano‐silica as potential system for carrying streptomycin at nano‐scale drug delivery

A growing trend within nanomedicine has been the fabrication of self‐delivering supramolecular nanomedicines containing a high and fixed drug content ensuring eco‐friendly conditions. This study reports on green synthesis of silica nanoparticles (Si‐NPs) using Azadirachta indica leaves extract as an effective chelating agent. X‐ray diffraction analysis and Fourier transform‐infra‐red spectroscopic examination were studied. Scanning electron microscopy analysis revealed that the average size of particles formed via plant extract as reducing agent without any surfactant is in the range of 100–170 nm while addition of cetyltrimethyl ammonium bromide were more uniform with 200 nm in size. Streptomycin as model drug was successfully loaded to green synthesised Si‐NPs, sustain release of the drug from this conjugate unit were examined. Prolong release pattern of the adsorbed drug ensure that Si‐NPs have great potential in nano‐drug delivery keeping the environment preferably biocompatible, future cytotoxic studies in this connection is helpful in achieving safe mode for nano‐drug delivery.Inspec keywords: silicon compounds, nanofabrication, nanomedicine, drug delivery systems, nanoparticles, X‐ray diffraction, Fourier transform infrared spectra, scanning electron microscopyOther keywords: nanosilica, streptomycin, nanoscale drug delivery, nanomedicine, silica nanoparticles, Azadirachta indica leaves extract, X‐ray diffraction analysis, Fourier transform‐infrared spectroscopy, scanning electron microscopy, cetyltrimethyl ammonium bromide, SiO₂      

Green synthesised zinc oxide nanostructures through Periploca aphylla extract shows tremendous antibacterial potential against multidrug resistant pathogens

To grapple with multidrug resistant bacterial infections, implementations of antibacterial nanomedicines have gained prime attention of the researchers across the globe. Nowadays, zinc oxide (ZnO) at nano‐scale has emerged as a promising antibacterial therapeutic agent. Keeping this in view, ZnO nanostructures (ZnO‐NS) have been synthesised through reduction by P. aphylla aqueous extract without the utilisation of any acid or base. Structural examinations via scanning electron microscopy (SEM) and X‐ray diffraction have revealed pure phase morphology with highly homogenised average particle size of 18 nm. SEM findings were further supplemented by transmission electron microscopy examinations. The characteristic Zn–O peak has been observed around 363 nm using ultra‐violet–visible spectroscopy. Fourier‐transform infrared spectroscopy examination has also confirmed the formation of ZnO‐NS through detection of Zn–O bond vibration frequencies. To check the superior antibacterial activity of ZnO‐NS, the authors'' team has performed disc diffusion assay and colony forming unit testing against multidrug resistant E. coli, S. marcescens and E. cloacae. Furthermore, protein kinase inhibition assay and cytotoxicity examinations have revealed that green fabricated ZnO‐NS are non‐hazardous, economical, environmental friendly and possess tremendous potential to treat lethal infections caused by multidrug resistant pathogens.Inspec keywords: nanomedicine, zinc compounds, II‐VI semiconductors, wide band gap semiconductors, nanoparticles, scanning electron microscopy, X‐ray diffraction, antibacterial activity, transmission electron microscopy, particle size, Fourier transform infrared spectra, ultraviolet spectra, visible spectra, enzymes, biochemistry, molecular biophysics, microorganisms, drugs, toxicology, bonds (chemical), semiconductor growth, nanofabrication, vibrational modesOther keywords: green synthesised zinc oxide nanostructures, Periploca aphylla extract, antibacterial potential, multidrug resistant pathogens, multidrug resistant bacterial infections, antibacterial nanomedicines, P. aphylla aqueous extract, structural examinations, scanning electron microscopy, X‐ray diffraction, pure phase morphology, homogenised average particle size, SEM, transmission electron microscopy, Fourier‐transform infrared spectroscopy, bond vibration frequency, antibacterial activity, disc diffusion assay, colony forming unit testing, S. marcescens, E. cloacae, E. coli, ultraviolet‐visible spectroscopy, protein kinase inhibition assay, cytotoxicity, lethal infections, ZnO     

Bilayer SiO2 Nanorod Arrays as Omnidirectional and Thermally Stable Antireflective Coating

Nature instigates researchers significantly in imitating to engender comparable properties using artificial methods, which unlocks developing trend in material science and engineering progress. Fabricating graded‐index nanostructures is an effective approach to tune and generate similar properties artificially such as the moth's eye antireflectance (AR) or lotus like superhydrophobicity. Herein, Bilayer AR coatings with periodically arranged SiO₂ hierarchical nanostructures resembling moth eyes are fabricated on dense SiO₂ matrix base layer using the versatile route of glancing angle deposition technique (GLAD). The refractive indices of monolayer SiO₂ are tuned from 1.46 to 1.08 by changing the deposition angle (α) from 0 to 88°. The fabricated bilayer SiO₂ AR (BSAR) film possess high optical omnidirectional broadband transparency and tunability at a desired wavelength range showing <1% reflectance. The present AR design is flexible and practically applicable to various supporting substrate materials (η varies from 1.45 to 1.9). Furthermore, the omnidirectional BSAR films show multiple functions including enhanced mechanical strength, the thermal stability (up to 300 °C), and hydrophobic capability with a water contact angle (CA) of 147° to withstand under humid environment. This multipurpose coating provides an intriguing route in optics field for imminent research.

     

Quantum Inspired Broadband Photonic Absorber: Potential Application as Solar Sail along with Mobility Analysis

Electromagnetic wideband absorption is still perceived as a critical and formidable challenge to address with an unambiguous photonic absorber. Subwavelength metamaterial (MM) unit cells with unique and controlled features have recently gained considerable interest. However, meta-atoms, generated using a quantum-inspired pattern distribution, are underwhelming in existing literature to design photonic absorbers and their potential application to manufacture solar sails is still quite uncommon. In this article, to create a flexible, polarization-insensitive, ultrathin, and broadband MM absorber, quantum interference pattern-inspired design is utilized. Herein, a novel approach to fabricating solar sails for the space exploration incorporates the proposed broadband photonic absorber rather than conventional reflectors. The quantum-inspired meta-absorber (QIMA) exhibits an absorption of over 91% for the visible domain, i.e., 380–800 nm under a conventional plane-polarized source. It is shown in the study that broadband absorbers are almost equivalent to excellent reflectors to design the solar sails in terms of the time-averaged force calculated by utilizing the Maxwell stress tensor method. Thus, the QIMA has the potential to be a viable alternative to reflectors in the design of futuristic solar sails for space exploration. The interference theory model is also utilized to assure the dependability of calculated data, and additionally, the standard AM1.5 solar spectrum is utilized to demonstrate the QIMA's solar-harvesting potentiality.     

Model-driven assessment of system dependability

Designers of complex real-time systems need to address dependability requirements early on in the development process. This paper presents a model-based approach that allows developers to analyse the dependability of use cases and to discover more reliable and safe ways of designing the interactions of the system with the environment. The hardware design and the dependability of the hardware to be used also needs to be considered. We use a probabilistic extension of statecharts to formally model the interaction requirements defined in the use cases. The model is then evaluated analytically based on the success and failure probabilities of events. The analysis may lead to further refinement of the use cases by introducing detection and recovery measures to ensure dependable system interaction. A visual modelling environment for our extended statecharts formalism supporting automatic probability analysis has been implemented in AToM³, A Tool for Multi-formalism and Meta-Modelling. Our approach is illustrated with an elevator control system case study.

Exploring pre-service teachers' beliefs about using Web 2.0 technologies in K-12 classroom

This qualitative study explored pre-service teachers' behavioral, normative, and control beliefs regarding their intentions to use Web 2.0 technologies in their future classrooms. The Theory of Planned Behavior (TPB) was used as the theoretical framework (Ajzen, 1991) to understand these beliefs and pre-service teachers' intentions for why they want to use Web 2.0 technologies. According to Ajzen's TPB, the behavioral beliefs are based on attitude toward outcomes or consequences of using Web 2.0, the normative beliefs depend on social support and social pressure to use Web 2.0, and the control beliefs lay the foundation of perceived behavioral control over using Web 2.0 in a classroom. Data were collected from open-ended survey questions (n = 190), semi-structured interviews (n = 12) and end of semester reflections (n = 12). Findings suggest that pre-service teachers' intentions to use Web 2.0 technologies are related to their beliefs about the value of these technologies for improving student learning and engagement, its ease of use (behavioral beliefs), its ability to meet the needs/expectations of digital age students (normative beliefs), the participants' high self-efficacy in use, and its potential for affording students anytime/anywhere access to learning and interaction (control beliefs). From these results, we recommend that teacher educators should target these beliefs within teacher development programs to prepare pre-service teachers for successful use of Web 2.0 technologies in their future K-12 classrooms.     

Standardization problem of author affiliations in citation indexes

Academic effectiveness of universities is measured with the number of publications and citations. However, accessing all the publications of a university reveals a challenge related to the mistakes and standardization problems in citation indexes. The main aim of this study is to seek a solution for the unstandardized addresses and publication loss of universities with regard to this problem. To achieve this, all Turkey-addressed publications published between 1928 and 2009 were analyzed and evaluated deeply. The results show that the main mistakes are based on character or spelling, indexing and translation errors. Mentioned errors effect international visibility of universities negatively, make bibliometric studies based on affiliations unreliable and reveal incorrect university rankings. To inhibit these negative effects, an algorithm was created with finite state technique by using Nooj Transducer. Frequently used 47 different affiliation variations for Hacettepe University apart from “Hacettepe Univ” and “Univ Hacettepe” were determined by the help of finite state grammar graphs. In conclusion, this study presents some reasons of the inconsistencies for university rankings. It is suggested that, mistakes and standardization issues should be considered by librarians, authors, editors, policy makers and managers to be able to solve these problems.