Effect of coagulant addition on the sedimentation of a surfactant-containing washing solution used for phenanthrene-contaminated soil

The coagulation of soil particles from a soil-washing solution containing the nonionic surfactant Triton X-100 (TX100) was investigated using various coagulants, such as chitosan (CS), polyacrylamide (PAA), and polyaluminum chloride (PAC). Soil contaminated with phenanthrene (PHE) was washed with aqueous TX100 solutions at concentrations ranging from 0.1 to 20 g/L. The effectiveness of CS (5 mg/L) as a coagulant in the system was compared with PAA (50mg/L) and PAC (50 mg/L), and the results indicated that the system with CS exhibited a more effective separation of soil than those with PAA and PAC. The removal efficiency of PHE (R _j =81.7%) and the selective separation factor (SSF=14.2) at 10 g/L TX100 were the highest for the system with CS (5 mg/L), indicating that the selection of CS as a coagulant in surfactant-mediated soil washing markedly improved both PHE removal and soil separation.     

Evaluation of Putative Allelochemicals in Rice Root Exudates for Their Role in the Suppression of Arrowhead Root Growth

In previous studies, 15 putative allelopathic compounds detected in rice root exudates were quantified by GC/MS/MS. In this study, multiple regression analysis on these compounds determined that five selected phenolics, namely caffeic, p-hydroxybenzoic, vanillic, syringic, and p-coumaric acids, from rice exudates were best correlated with the observed allelopathic effect on arrowhead (Sagittaria montevidensis) root growth. Despite this positive association, determination of the phenolic acid dose-response curve established that the amount quantified in the exudates was much lower than the required threshold concentration for arrowhead inhibition. A similar dose-response curve resulted from a combination of all 15 quantified compounds. Significant differences between the amounts of trans-ferulic acid, abietic acid, and an indole also existed between allelopathic and non-allelopathic rice cultivars. The potential roles of these three compounds in rice allelopathy were examined by chemoassay. Overall, neither the addition of trans-ferulic acid nor 5-hydroxyindole-3-acetic acid to the phenolic mix significantly contributed to phytotoxicity, although at higher concentrations, trans-ferulic acid appeared to act antagonistically to the phytotoxic effects of the phenolic mix. The addition of abietic acid also decreased the inhibitory effect of the phenolic mix. These studies indicate that the compounds quantified are not directly responsible for the observed allelopathic response. It is possible that the amount of phenolic acids may be indirectly related to the chemicals finally responsible for the observed allelopathic effect.     

Analytical prediction of resonant frequencies of annular stacked dielectric resonator antennas

The method of stacking dielectric resonators for designing multiband and wideband antennas has gained much attention in recent times. However, the existing works lack any theoretical framework for the prediction of resonant frequencies of such stacked structures. In this work, a formal analysis using a cavity model with the mode matching technique is presented to determine all the existing resonant frequencies of annular stacked cylindrical dielectric resonator antennas with and without air gap. The analysis is done separately considering the outermost sidewall of the stack as both perfect magnetic conductor and imperfect magnetic conductor. The theoretical findings are extensively validated against numerous simulations, as well as against a fabricated prototype. It is observed that the perfect magnetic wall condition provides results that are more accurate. The closed‐form equation derived in this work not only helps in accurately predicting the resonant frequencies but also reduces the run‐time manifolds compared to that of the existing trial and error based methods of design using software simulations.     

Mechanical characterization of microwave sintered zinc oxide

The mechanical characterization of microwave sintered zinc oxide disks is reported. The microwave sintering was done with a specially designed applicator placed in a domestic microwave oven operating at a frequency of 2.45 GHz to a maximum power output of 800 Watt. These samples with a wide variation of density and hence, of open pore volume percentage, were characterized in terms of its elastic modulus determination by ultrasonic time of flight measurement using a 15 MHz transducer. In addition, the load dependence of the microhardness was examined for the range of loads 0.1–20 N. Finally, the fracture toughness data (K _IC) was obtained using the indentation technique.     

Enhanced mechanical strength of chitosan hydrogel beads by impregnation with carbon nanotubes

Chitosan (CS) hydrogel beads were impregnated with carbon nanotubes (CNTs), and their mechanical strength, acid stability and adsorption capacity to the anionic dye, Congo red (CR), were investigated by comparing with a conventional reinforcing method of cross-linking with epichlorohydrin (ECH). CS/CNT hydrogel beads were manufactured by dispersing CNTs (0.01 wt.%) with cetyltrimethylammonium bromide (CTAB) (0.05 wt.%) into CS solution (1 wt.%). Maximum endurable force at complete breakdown of CS hydrogel beads increased from 1.87 to 7.62 N with incorporation of CNTs and its adsorption capacity increased from 178.32 to 423.34 mg g⁻¹ for adsorption of CR.     

One dimensional nanostructured materials

The quest for materials with molecular scale properties that can satisfy the demands of the 21st century has led to the development of one dimensional nanostructures, ODNS. Nearly, every class of traditional material has an ODNS counterpart. ODNS has a profound impact in nanoelectronics, nanodevices and systems, nanocomposite materials, alternative energy resources and national security. The interface of nanoscience and technology with biological and therapeutic sciences is expected to radically improve the ability to provide efficient treatments in otherwise impossible situations. Ironically, the huge investment in the past few years across the globe is yet to bring the real benefit of nanotechnology in day to day life. While scientists and engineers are working towards this goal, concerns about the possible harmful effects of the high aspect ratio materials are increasing every day. Following is an effort to assimilate most of the aforementioned aspects including the entire gamut of ODNS, i.e., elements, ceramics, polymers and composites, with a brief discussion on CNT and toxicology. The focus of this article is mainly on the science behind the synthesis and properties of the ODNS rather than the device fabrication. However, a few challenges in the field of device fabrication are mentioned in appropriate contexts. Possible mechanisms of the ODNS evolution from various methods, such as vapor liquid solid (VLS), template based and electrochemically induced growth, have been discussed in detail. Electron microscopy analysis has received special focus in determining the unique structural features. The article concludes by discussing current research related to environment and toxicology effects and current challenges in this rapidly evolving field.     

A secured image steganography method based on ballot transform and genetic algorithm

Multimedia Tools and Applications - Rapid advances in digital technology have facilitated us to transfer a huge amount of electronic files over the internet. But in the presence of malicious...     

Phenolic,apparent antioxidant and nutritional composition of quinoa (Chenopodium quinoa Willd.) seeds

Quinoa, a gluten-free pseudocereal, has a nutrient and phytochemical profile which may benefit health. Our aim was to investigate the variability in the phenolic and apparent antioxidant content of different quinoa varieties to identify a variety with a high phytochemical content to use in a quinoa-enriched bread. The results showed that free phenolics contributed most (50–83%) to total phenolic content compared with conjugated or bound forms. Apparent antioxidant activities measured by FRAP, ABTS+• and DPPH of free, conjugated and bound extracts were broadly similar, except for free antioxidants when determined by FRAP, which were higher. Phenolic content was positively correlated with FRAP and ABTS+• apparent antioxidant activity. Quinoa samples had a high protein content (13.5 g/100 g dry weight), with a well-balanced amino acid profile. Incorporation of quinoa into baked products such as bread is proposed as a way to deliver this healthy whole-grain cereal into the diet.