Arsenic removal using silver-impregnated Prosopis spicigera L. wood (PSLW) activated carbon: batch and column studies

Silver-impregnated carbon (SIC) and its precursor (un-impregnated) derived from an easily available low cost plant material Prosopis spicigera L. wood (PSLW) carbon was investigated for their ability to remove arsenic from aqueous solutions in batch and column experiments. Arsenic uptake has no regular trend with increasing pH; contains two adsorption maxima, the first adsorption maximum at pH 4.0 and a second adsorption maximum at pH 10.0. The extent of As (III) removal increased with increase in temperature. As (III) sorption kinetics was well fitted by pseudo second order with pore diffusion as rate determining step. The applicability of Langmuir isotherm suggests the formation of monolayer coverage of As (III) at the outer surface of the adsorbent. Thermodynamic parameters show that the adsorption was spontaneous and endothermic in nature. Column experiments were done using Thomas model, the maximum adsorption capacity of SIC was found to be 9.36 mg/g.Keywords: Adsorption, Arsenic, batch adsorption, langmuir isotherm, silver-impregnated carbon (SIC), Thomas mode

A study on water hyacinth Eichhornia crassipes as oil sorbent

The sorption of diesel, lubricant and castor oils onto different parts (root, stem and leaf) of the dry biomass water hyacinth was studied at the laboratory scale. The parts of the aquapyte water hyacinth (Eichhornia Crassipes) were characterized by physico-chemical methods and the characteristics were used to elucidate the oil sorption process. Hydrophobicity, wettability (capillarity), buoyancy and sorption capacity of oils in the presence/absence of water were studied to evaluate the suitability of the sorbent for application. In all the three sorbents, theoil sorption capacity increases with the increase of oil film thickness. However of the three parts, the stem has a greater sorption capacity of 9.3, 7.8 and 11.08 g/g for the three oils such as diesel, lubricant and castor oils respectively, even though the root of water hyacinth showed a higher hydrophobicity and surface area. These sorption capacities are comparable with widely used commercial oil sorbent such as nonwoven polypropylene which has a sorption capacity in the range of 10-16 g/g

Effect of okra plant resistance on transmission rate of okra enation leaf curl virus by its vector whitefly, Bemisia tabaci

The present study aimed to investigate the effect of age of the okra plants that showed varying whitefly resistance responses on the transmission rate of okra enation leaf curl virus (OELCV) by its vector whitefly Bemisia tabaci. The OELCV infected whitefly adults were collected from whitefly colonies and were challenged on the test okra accessions (Upl mona 2, Co 1, Arka anamika and AE 64) of differential ages which were individually caged (7, 10 and 15 d after germination) with glass chimney and the number of such whiteflies used were at the rate of 2, 4, 6, 8, 10, 12, 14 and 20 adults per plant. Observations were made on the virus symptom expression 30 d after challenge. The efficiency of transmission was determined. The efficiency of transmission of OELCV was the highest (maximum T and P*, 0.80, 1.00 and 0.08, 0.10) when 7 d old seedlings were inoculated (Arka anamika and AE 64 respectively) and transmission had decreased as the age of seedlings increased. The estimated transmission rate for single whitefly (P*) increased with an increase in the number of whiteflies used per plant. Okra plant resistance to B. tabaci significantly changed the transmission rates of OELCV on okra. Understanding the resistance mechanisms of the okra accessions and interactions between plant viruses and their insect host can pave the way for novel approaches to protect plants from virus infection

Transmogrifying Fuzzy Vortices

We show that the construction of vortex solitons of the noncommutative Abelian-Higgs model can be extended to a critically coupled gauged linear sigma model with Fayet-Illiopolous D-terms. Like its commutative counterpart, this fuzzy linear sigma model has a rich spectrum of BPS solutions. We offer an explicit construction of the degree$-k$ static semilocal vortex and study in some detail the infinite coupling limit in which it descends to a degree$-k$ \C\Pk^{N} instanton. This relation between the fuzzy vortex and noncommutative lump is used to suggest an interpretation of the noncommutative sigma model soliton as tilted D-strings stretched between an NS5-brane and a stack of D3-branes in type IIB superstring theory.Comment: 21 pages, 4 figures, LaTeX(JHEP3

Development of silver nanoparticle stabilized poly (aniline -co- pyrrole) for electrochemical application

Silver nanoparticles (Ag-Nps) decorated conducting copolymers of aniline and pyrrole monomers [poly (aniline -copyrrole)] have been synthesized through a simple in-situ chemical oxidative co-polymerization. The formation and characteristics of poly (aniline -co- pyrrole)-Ag have been confirmed using microscopic and spectroscopic techniques. The synthesized nanocomposite has been characterized using scanning electron microscopy, fourier transform infra-red spectroscopy, RAMAN spectroscopy, X-ray diffraction, thermogravimetric analysis and UV-Visible spectroscopy have been used to identify the phase, morphology and thermal stability. The composite has been used to modify the glassy carbon electrode to obtain poly (aniline -co- pyrrole)-Ag/ GCE. Cyclic voltammetry and square wave voltammetry have been used for the electrochemical sensing of uric acid. The modified GC electrode has shown an excellent electrocatalytic oxidation of uric acid to allantoin at neutral pH of phosphate buffer solution. The proposed sensor thus involves simple fabrication with high accuracy and sensitivity

Ligand-receptor promiscuity enables cellular addressing

In multicellular organisms, secreted ligands selectively activate, or "address," specific target cell populations to control cell fate decision-making and other processes. Key cell-cell communication pathways use multiple promiscuously interacting ligands and receptors, provoking the question of how addressing specificity can emerge from molecular promiscuity. To investigate this issue, we developed a general mathematical modeling framework based on the bone morphogenetic protein (BMP) pathway architecture. We find that promiscuously interacting ligand-receptor systems allow a small number of ligands, acting in combinations, to address a larger number of individual cell types, each defined by its receptor expression profile. Promiscuous systems outperform seemingly more specific one-to-one signaling architectures in addressing capacity. Combinatorial addressing extends to groups of cell types, is robust to receptor expression noise, grows more powerful with increasing receptor multiplicity, and is maximized by specific biochemical parameter relationships. Together, these results identify fundamental design principles governing cell addressing by ligand combinations

Holonomy in the Schwarzschild-Droste Geometry

Parallel transport of vectors in curved spacetimes generally results in a deficit angle between the directions of the initial and final vectors. We examine such holonomy in the Schwarzschild-Droste geometry and find a number of interesting features that are not widely known. For example, parallel transport around circular orbits results in a quantized band structure of holonomy invariance. We also examine radial holonomy and extend the analysis to spinors and to the Reissner-Nordstr\"om metric, where we find qualitatively different behavior for the extremal ($Q = M$) case. Our calculations provide a toolbox that will hopefully be useful in the investigation of quantum parallel transport in Hilbert-fibered spacetimes.Comment: 18 Latex pages, 3 figures. Second replacement. This version as published in CQG with some misprints correcte

About the self-dual Chern-Simons system and Toda field theories on the noncommutative plane

The relation of the noncommutative self-dual Chern-Simons (NCSDCS) system to the noncommutative generalizations of Toda and of affine Toda field theories is investigated more deeply. This paper continues the programme initiated in $JHEP {\bf 10} (2005) 071$, where it was presented how it is possible to define Toda field theories through second order differential equation systems starting from the NCSDCS system. Here we show that using the connection of the NCSDCS to the noncommutative chiral model, exact solutions of the Toda field theories can be also constructed by means of the noncommutative extension of the uniton method proposed in $JHEP {\bf 0408} (2004) 054$ by Ki-Myeong Lee. Particularly some specific solutions of the nc Liouville model are explicit constructed.Comment: 24 page