Innovative multi‐processed N‐doped carbon and Fe3O4 cathode for enhanced bioelectro‐Fenton microbial fuel cell performance

A novel bioelectro‐Fenton microbial fuel cell (BEF‐MFC) cathode has been fabricated by modification of electrode using multi‐processing of nitrogen‐doped carbon (NDC)/nano‐Fe₃O₄ method with the aims of cost‐effectiveness, high oxygen reduction reaction (ORR) efficiency, and power performance enhancement. In this study, BEF‐MFC with carbon cloth (CC) cathode pyrolyzed with NDC‐M100/Fe₃O₄ at 700°C achieved higher ORR activity compared with the commercial Pt/C under same operational conditions. It also exhibited excellent crystalline structure according to high‐resolution transmission electron microscope (HRTEM) analysis. Moreover, using NDCN/Fe₃O₄ can facilitate further Fenton‐like reaction for the treatment of wastewater. Chemical oxygen demand (COD) removal efficiency of the reactor was 78% with maximum power density of 1.57 W/m³ in 216 hours. Thus, an innovative multi‐processing method with feasibility for enhanced wastewater treatment and improved power performance of the MFC was investigated. This can be effectively applied in related alternative energy production techniques and bio‐electrochemical systems in the future.     

Understanding the structure of the adhesive plaque of Amphibalanus reticulatus

The barnacle, Amphibalanus reticulatus, is a common fouler in the Indian marine waters and is found to attach to a wide variety of natural and man-made surfaces. The shells of the barnacles remain attached to the substrate irrespective of whether the barnacle is alive or dead and details of dried shells are relatively less explored. The dried adhesive plaque of the barnacles attached to polymethylmethacrylate (PMMA) substrates were isolated and subjected to several structural characterization studies like X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results report the presence of calcite nano-crystallites and amide II groups corresponding to the adhesive protein. The characteristic concentric ring pattern of barnacle base-plate structure, under higher magnification using SEM, appears to be formed of alternate calcite bricks and cement duct openings with an increasing separation distance between adjacent rings. The shear strength studies of barnacles of varying size indicate a direct correspondence to the base-plate diameter.     

Carotenoid composition and retinol equivalent in plants of nutritional and medicinal importance: Efficacy of β-carotene from Chenopodiumalbum in retinol-deficient rats

This study aimed to (1) quantify carotenoids in leafy vegetables and plants of nutritional and medicinal importance, (2) evaluate retinol equivalent (RE) of provitamin-A carotenoids and (3) determine efficacy of β-carotene from Chenopodium album and to compare with retinol formed on feeding to retinol-deficient rats for 3 weeks. β-Carotene and lutein contents (mg/100 g dry weight) ranged from 1.5 to 120 and 11.7 to 185 (leafy greens) and 0.4 to 34.7 and 11.8 to 679 (medicinal plants) whereas, α-carotene ranged from 0.3 to 35.6 (leafy greens) and 0.1 to 15.7 (medicinal plants). RE values (mg%) ranged from 0.4 to 20 and 0.42 to 5.8 in leafy greens and medicinal plants. Efficacy of β-carotene (2400 μg/kg diet) from C. album in retinol-deficient rats revealed a 93.6% rise in plasma retinol levels from 0.53 to 8.4 μM. The plants analysed are a good source of retinol precursors and biologically active lutein; therefore can be exploited to meet carotenoid requirements.     

Dysregulation of microRNA and Intracerebral Hemorrhage: Roles in Neuroinflammation

Intracerebral hemorrhage (ICH) is a major public health problem and devastating subtype of stroke with high morbidity and mortality. Notably, there is no effective treatment for ICH. Neuroinflammation, a pathological hallmark of ICH, contributes to both brain injury and repair and hence, it is regarded as a potential target for therapeutic intervention. Recent studies document that microRNAs, small non-coding RNA molecules, can regulate inflammatory brain response after ICH and are viable molecular targets to alter brain function. Therefore, there is an escalating interest in studying the role of microRNAs in the pathophysiology of ICH. Herein, we provide, for the first time, an overview of the microRNAs that play roles in ICH-induced neuroinflammation and identify the critical knowledge gap in the field, as it would help design future studies.     

Investigation on the development of sturdy bioactive hydrogel beads

Biocatalytic hydrogel beads, which retain higher activity, expand, and contract with changes in pH, having biocompatibility, are developed. Composite spherical beads of chitosan having a diameter of 1–2 mm were prepared by ionic gelation using sodium tripolyphosphate (TPP). Above 3% TPP, the activity of the enzyme decreases. The mechanical strength of the chitosan–TPP beads was further improved by the addition of clay or cassava starch granules. The immobilization of protease (fungal, Aspergillus) was done with glutaraldehyde crosslinking. The chitosan–starch hydrogel beads showed significant increase in firmness and stiffness when compared with chitosan–clay beads. The swelling studies show that the particles expand at pH 1.2 and contract at pH 7.4. The activity retention of the immobilized protease was as high as 70% and exhibited a high pH and lower temperature optima than the free enzyme. Chitosan–starch hydrogel beads exhibited degradation peaks at about 90–110°C in TGA analysis. The biocatalyst beads retained 85% of the original catalytic activity even after eight cycles of repeat use. The freeze‐dried beads has good storage stability and can be used either as artificial bioreactor systems in detergent or in therapeutic formulations © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Solvent extraction of hexavalent chromium with tetrabutyl ammonium bromide from aqueous solution

The extraction of hexavalent chromium (Cr) from aqueous solutions by tetrabutyl ammonium bromide (TBAB) salt in dichloromethane was investigated. The results indicated that the maximum extraction efficiency of Cr(VI) was at pH 1±0.1. The strippant 0.1 M sodium hydroxide, completely stripped Cr(VI) from the loaded solvent. The stripped solvent can be reused for extracting Cr(VI). After five extraction cycles, the dichloromethane showed no significant loss in volume and retains the same extracting ability. The solvent extraction method was applied for the removal and recovery of Cr(VI) from real chromeplating wastewater and found to be satisfactory.     

Characterization studies on plasma sprayed (AT/HA) bi-layered nano ceramics coating on biomedical commercially pure titanium dental implant

Hydroxyapatite (HA), Al₂O₃–13 wt%TiO₂ (AT) nanoparticles coated on bioactive commercially pure titanium (Cp-Ti) implant were fabricated by plasma spray coating technique. The fabricated monolayer AT, HA film of thickness 75 μm and bilayer (AT/HA) of thickness 150 μm and the coated film surface crystallinity, morphology and phases were investigated in terms of X-ray diffraction, SEM, FT-Raman spectroscopy. In this work, nanostructure AT, HA powders were plasma sprayed on the biomedical Cp-Ti implant surface improve corrosion resistance, and microhardness, surface roughness values compared to uncoated surface. Electrochemical corrosion test was carried out by simulated body fluid (SBF) with ionic concentrations comparable to that of human blood plasma and this result shows that improved corrosion resistance, for the bilayer (AT/HA) coated surface compared to a monolayer AT, HA coated surface. For Al₂O₃ addition with 13 wt%TiO₂ ceramics powder reinforced coating which can act as a barrier for the metal ion released from the implant surface. The in vitro analysis of the bilayer coated implant was good agreement with bone osteoinduction in the biological environment.     

Green synthesis of zinc oxide nanoparticles by aloe barbadensis miller leaf extract: Structure and optical properties

Biological methods for nanoparticle synthesis using microorganisms, enzymes, and plants or plant extracts have been suggested as possible ecofriendly alternatives to chemical and physical methods. In this paper, we report on the synthesis of nanostructured zinc oxide particles by both chemical and biological method. Highly stable and spherical zinc oxide nanoparticles are produced by using zinc nitrate and Aloe vera leaf extract. Greater than 95% conversion to nanoparticles has been achieved with aloe leaf broth concentration greater than 25%. Structural, morphological and optical properties of the synthesized nanoparticles have been characterized by using UV-Vis spectrophotometer, FTIR, Photoluminescence, SEM, TEM and XRD analysis. SEM and TEM analysis shows that the zinc oxide nanoparticles prepared were poly dispersed and the average size ranged from 25 to 40 nm. The particles obtained have been found to be predominantly spherical and the particle size could be controlled by varying the concentrations of leaf broth solution.     

Preconcentration and separation of copper, nickel and zinc in aqueous samples by flame atomic absorption spectrometry after column solid-phase extraction onto MWCNTs impregnated with D2EHPA-TOPO mixture

A solid phase extraction method has been developed for the determination of copper, nickel and zinc ions in natural water samples. This method is based on the adsorption of copper, nickel and zinc on multiwalled carbon nanotubes (MWCNTs) impregnated with di-(2-ethyl hexyl phosphoric acid) (D2EHPA) and tri-n-octyl phosphine oxide (TOPO). The influence of parameters such as pH of the aqueous solution, amount of adsorbent, flow rates of the sample and eluent, matrix effects and D2EHPA-TOPO concentration have been investigated. Desorption studies have been carried out with 2 mol L(-1) HNO(3). The copper, nickel and zinc concentrations were determined by flame atomic absorption spectrometry. The results indicated that the maximum adsorption of copper, nickel and zinc is at pH 5.0 with 500 mg of MWCNTs. The detection limits by three sigma were 50 μg L(-1) for copper, 40 μg L(-1) for nickel and 60 μg L(-1) zinc. The highest enrichment factors were found to be 25. The adsorption capacity of MWCNTs-D2EHPA-TOPO was found to be 4.90 mg g(-1) for copper, 4.78 mg g(-1) for nickel and 4.82 mg g(-1) for zinc. The developed method was applied for the determination of copper, nickel and zinc in electroplating wastewater and real water sample with satisfactory results (R.S.D.'s <10%).     

Performance Analysis of Subspace Based Downlink Channel Estimation for W-CDMA Systems Using Chaotic Codes

This paper presents blind channel estimation for downlink W-CDMA system that employs chaotic codes and Walsh codes for spreading information bits of the multiple users. In a W-CDMA system, while transmitting over multipath channels, both intersymbol interference (ISI) as a result of Inter Chip Interference and multiple access interference (MAI) cannot be easily eliminated. Although it is possible to design multiuser detectors that suppress MAI and ISI, these detectors often require explicit knowledge of at least the desired users’ signature waveform. Earlier work focused on a subspace based channel estimation algorithm for asynchronous CDMA systems to estimate the multiple users’ symbols, where only AWGN channel was considered. In our work, we study a similar subspace-based signature waveform estimation algorithm for downlink W-CDMA systems, which use chaotic codes instead of pseudo random codes, that provide estimates of the multiuser channel by exploiting structural information of the data output at the base station. In particular, we show that the subspace of the (data+noise) matrix contains sufficient information for unique determination of channels, and hence, the signature waveforms and signal constellation. We consider Rayleigh and Rician fading channel model to quantify the multipath channel effects. Performance measures like bit error rate and root mean square error are plotted for both chaotic codes and Walsh codes under Rayleigh and Rician fading channels.