Development and Characterization of Inorganic-Organic (Si-O-Al) Hybrid Geopolymeric Precursors via Solid State Method

Silicon - In this study, an innovative one part, solution free concept applied for the development of hybrid inorganic–organic geopolymeric precursors having Si-O-Al networks at the precursor...     

A cubic B-spline quasi-interpolation algorithm to capture the pattern formation of coupled reaction-diffusion models

Diffusion plays a significant role in complex pattern formulations occurred in biological and chemical reactions. In this work, the authors study the effect of diffusion in coupled reaction-diffusion systems named the Gray-Scott model for complex pattern formation with the help of cubic B-spline quasi-interpolation (CBSQI) method and capture various formates of these patterns. The idea of Kronecker product is used first time with CBSQI method for 2D problems. Linear stability analysis of the reaction-diffusion system as well as stability of the proposed method is studied. Four test problems are considered to check the accuracy and efficiency of the method and found the stable patterns.

     

Linearly tapered meander line cross dipole circularly polarized antenna for UHF RFID tag applications

In this article, a circularly polarized antenna for ultra‐high frequency radio frequency identification (RFID) tag is presented. The circular polarization is realized by two orthogonal, unequal length linearly tapered meander line cross dipoles. The meander structure with capacitive tip loading is used for size miniaturization of the antenna. A modified T‐match network is employed to feed the cross dipole structure. The measured 10‐dB return loss bandwidth of the cross dipole antenna is 17 MHz (908‐923 MHz) and the corresponding 3‐dB axial ratio bandwidth is 6 MHz (912‐918 MHz). The overall size of the proposed antenna is 0.17λ₀ × 0.17λ₀ at 915 MHz. The maximum read range between the reader and the tag with the proposed antenna is 4.7 m larger than the analogous linearly polarized tag antenna due to the reduction in polarization loss between the tag and reader antennas. Thus, a maximum read range of 15.66 m with the gain of 1.28 dBic is achieved at 915 MHz.     

Dual‐band circularly polarized dielectric resonator antenna for wireless applications

This letter investigates an integrated antenna configuration for WLAN/WiMAX applications. The proposed composite antenna configuration is simply the grouping of ring dielectric resonator along with reformed square‐shaped slot antenna. Three significant characteristics of proposed article are: (1) aperture act as magnetic dipole and excite HE_11δ mode in ring dielectric resonator antenna; (2) reforming of square aperture generates orthogonal modes in ring DRA and creates CP in lower frequency band; (3) annular‐shaped Microstrip line along with reformed square aperture creates CP wave in upper frequency band. With the purpose of certifying the simulated outcomes, prototype of proposed structure is fabricated and tested. Good settlement is to be got between experimental and software generated outcome. Experimental outcomes show that the proposed radiating structure is operating over 2 frequency bands that is, 2.88‐3.72 and 5.4‐5.95 GHz. Measured 3‐dB axial ratio bandwidth in lower and upper frequency band is approximately 9.52% (3.0‐3.4 GHz) and 5.85% (5.64‐5.98 GHz), respectively. These outcomes indicate that the proposed composite antenna structure is appropriate for WLAN and WiMAX applications.     

Context-Aware Holographic Communication Based on Semantic Knowledge Extraction

Augmented, mixed and virtual reality are changing the way people interact and communicate. Five dimensional communications and services, integrating information from all human senses are expected to emerge, together with holographic communications (HC), providing a truly immersive experience. HC presents a lot of challenges in terms of data gathering and transmission, demanding Artificial Intelligence empowered communication technologies such as 5G. The goal of the paper is to present a model of a context-aware holographic architecture for real time communication based on semantic knowledge extraction. This architecture will require analyzing, combining and developing methods and algorithms for: 3D human body model acquisition; semantic knowledge extraction with deep neural networks to predict human behaviour; analysis of biometric modalities; context-aware optimization of network resource allocation for the purpose of creating a multi-party, from-capturing-to-rendering HC framework. We illustrate its practical deployment in a scenario that can open new opportunities in user experience and business model innovation.

     

Effect of DC glow discharge treatment on the surface energy and surface resistivity of thin film of polypropylene

A change in the surface energy and surface resistivity of a thin film of polypropylene (PP) of thickness 100 μm was investigated, using direct current (DC) glow discharge. The thin film of the PP was treated for various discharge powers and treatment time and the modification in the surface energy and the surface resistivity was observed. To investigate the modification in the surface energy after DC glow discharge treatment, contact angle of two test liquids formamide and de‐ionized water over the surface of PP film was measured. By measuring the contact angle the change in surface energy and its two polar and dispersive components have been measured. It was observed that at a given power level of DC glow discharge surface energy and its polar component increases with increase of the treatment time, attains a maximum value, and then becomes almost constant. Correspondingly, with increase in surface energy, a decrease in surface resistivity was observed. Also, a change in surface morphology was observed by atomic force microscopy and by FT‐IR spectra generation of polar groups at the surface of PP film. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 767–772, 2007     

The subunit structure of human macrophage migration inhibitory factor: evidence for a trimer

The subunit structure of human macrophage migration inhibitoryfactor (MIF) has been studied by preliminary X-ray analysisof wild-type and selenomethionine-MIF and dynamic light scattering.Crystal form I of MIF belongs to space group P2₁2₁2₁ and isgrown from 2 M ammonium sulfate at pH 8.5. A native data sethas been collected to 2.4 Å resolution. Self-rotationstudies and V_m values indicate that three molecules per asymmetricunit are present A data set to 2.8 Å resolution has beencollected for crystal form II, which belongs to space groupP3¹21 or P3²21 and grows from 2 M ammonium sulfate, 2% polyethyleneglycol (average molecular mass 400), 0.1 M HEPES, pH 7.5. Three,four, five or six monomers in the asymmetric unit are consistentwith V_m values for this crystal form. Analysis of crystal formII containing selenomethionine-MIF indicates nine selenium sitesare present per asymmetric unit. Dynamic light scattering ofMIF suggests that the major form of the protein in solutionis a trimer. The results of these studies are in contrast toprevious reports indicating that MIF is a monomer or dimer.The subunit arrangement of MIF is similar to that of tumor necrosisfactor and suggests that signal transduction might require trimerizationof receptor subunits.     

External-loop fluidized bed airlift bioreactor (EFBAB) for the cometabolic biotransformation of 4-chlorophenol (4-cp) in the presence of phenol

The advantages from a 4-l external-loop inversed fluidized bed airlift bioreactor (EIFBAB) reported by Loh and Liu [2001. Chemical Engineering Science 56, 6171-6176] was synergized with preferential adsorption by granular activated carbon (GAC) for the enhanced cometabolic biotransformation of 4-chlorophenol (4-cp) in the presence of phenol as a growth substrate. This was achieved by incorporating a GAC fluidized bed in the lower part of the riser with the gas sparger relocated above this fluidized bed to avoid the presence of a 3-phase flow in the fluidized bed consequently providing larger gas holdup. Expanded polystyrene beads (EPS) were used as the supporting matrix for immobilizing Pseudomonas putida ATCC 49451, in the downcomer of the bioreactor. The hydrodynamics of the bioreactor system was characterized by studying the effect of the extent of valve opening, under cell-free condition, on gas holdup and liquid circulation velocity at different gas velocities and solids loading (EPS and GAC). The experimental data for gas holdup were modeled using power law correlations, while a Langmuir-Hinshelwood kinetics model was used for the liquid circulation velocity. The bioreactor was tested for batch cometabolic biotransformation of 4-cp in the presence of phenol at various concentration ratios of phenol and 4-cp (ranging from phenol: 4-cp to phenol: 4-cp) at 9% EPS loading and 2.8% (10 g) GAC loading. The 4-cp and phenol biotransformations were achieved successfully in the bioreactor system, which ascertained the feasibility of the bioreactor. Biotransformation of high 4-cp and phenol concentrations, which was oxygen limited, was also effectively achieved by increasing the gas holdup in the riser. This was possible in the current EFBAB system because of the synergistic effect of the GAC fluidized bed, the globe valve and cell immobilization by EPS.     

Investigation on the spring-in phenomenon of carbon nanofiber-glass fiber/polyester composites manufactured with vacuum assisted resin transfer molding

Process-induced residual stress arises in polymer composites as a result of mismatched resin contraction and fiber contraction during the cure stage. When a curved shell-like composite part is de-molded, the residual stress causes the spring-in phenomenon, in which the enclosed angle of the part becomes smaller than the angle of its mold. In this paper, a new approach is presented to control and reduce the spring-in angle by infusing a small amount of carbon nanofibers (CNFs) together with liquid resin into the glass fiber preform using vacuum assisted resin transfer molding (VARTM) process. The experimental results showed that the spring-in angles of the L-shaped composite specimens were effectively restrained by the CNFs. An analytical model and a 3-D FEA model were developed to predict the spring-in phenomenon and to understand the role of CNFs in reducing the spring-in angle. The models agreed with the experimental results reasonably well. Furthermore, the analytical model explains how the CNF-enhanced dimensional tolerance control is accomplished through the reductions in the matrix’s equivalent coefficient of thermal expansion and linear crosslinking shrinkage.