Adsorption of Co, Ni, Cu, and Zn on hydrous manganese dioxide from complex electrolyte solutions resembling sea water in major ion content

Adsorption of Co, Ni, Cu, and Zn onto a poorly crystalline hydrous manganese dioxide (delta-MnO2) has been studied in complex electrolyte solutions such as (a) 0.5 M NaCl+0.054 M MgCl2, (b) 0.5 M NaCl+0.028 M Na2SO4, and (c) artificial sea water prepared according to the standard literature method. These three solutions allow us to identify the specific effect of major cations, major anions, and the mixture of major cations and anions (including carbonate and bicarbonate) that is present in real sea water. The adsorption isotherm in major ion sea water at pH 7.25 indicates that while Co and Zn exhibit increases in adsorption with increase in concentration, Ni shows relatively poor adsorption, reaching a plateau at 0.075 mM concentration. The three trace metals (Co, Ni, and Zn) show Langmuirian behavior for adsorption at low concentration. It is generally observed that the fractional adsorption vs pH curve shifts to higher pH either in the presence of 0.054 M MgCl2 or in sea water. In the presence of 0.028 M Na2SO4 the fractional adsorption vs pH curve remains almost unchanged with respect to a 0.5 M NaCl solution. The competitive adsorption of one trace metal in the presence of other three in major ion sea water indicates that this phenomenon is more predominant with Ni and Zn than with Co and Cu.     

Determination of heats of aluminothermic redox reaction of V2O5 and MnO2

Differential thermal analysis has been used for quantitative determination of heats of aluminothermic redox reaction of MnO₂ and V₂O₅ over a wide range of temperatures. Heat of reaction V₂O₅?Al and MnO₂?Al systems have been determined using the calibration plot established. The experimentally determined values compare well with those predicted from thermodynamic data available in the literature. It has been found that V₂O₅?Al system involves a higher heat of reaction in comparison to the MnO₂?Al system.     

Oscillation of fourth order nonlinear neutral difference equations I

Oscillatory and asymptotic behaviour of solutions of a class of nonlinear fourth order neutral difference equations of the form

Counting spinning dyons in maximal supergravity: the Hodge-elliptic genus for tori

We consider M-theory compactified on \(T^4 \times T^2\) and describe the count of spinning 1/8-BPS states. This builds on the work of Maldacena–Moore–Strominger in the physics literature. It simultaneously provides a refinement of the recent mathematical work of Bryan–Oberdieck–Pandharipande–Yin and Oberdieck–Shen, which studied (non-motivic) reduced Donaldson–Thomas invariants of abelian surfaces and threefolds. As in previous work on \(K3 \times T^2\) compactification, we track angular momenta under both the \(SU(2)_L\) and \(SU(2)_R\) factors in the 5d little group, providing predictions for the relevant motivic curve counts.     

STUDY ON PHOTODYNAMIC AND PHOTORESPONSIVE AZO POLYELECTROLYTES*

Several kinds of novel azobenzene-containing polyelectrolytes with special molecular design have been developedfrom acryloyl chloride or epoxy based precursor polymers. The acryloyl chloride based precursor polymer, poly(acryloylchloride), was prepared by free radical polymerization of acryloyl chloride. The azo polyelectrolytes were prepared by anesterification reaction between the precursor polymer and corresponding azo chromophores containing a reactive hydroxylgroup, followed by hydrolysis of the unreacted acyl chloride groups. The epoxy based precursor polymer was prepared by thereaction between 1,4-cyclohexanedimethanol diglycidyl ether and aniline, and postfunctionalized by azo coupling reaction toform azo polymers containing chromophores with ionizable groups. The polyelectrolytes were characterized by elementalanalysis, ~1H-NMR, IR and UV-Vis spectroscopy. The photodynamic and photoresponsive properties, as well as self-assemblyof these azo polyelectrolytes are reported in this paperp.     

Biosurfactants—An Overview

The large structural and functional variety of bio-surfactants (BS), which are produced by microorganisms, leads to the use of several methods to study these amphiphilic molecules. This review seeks to consolidate information on various surface-active product extraction techniques, microbiological screening methodologies, and analytical terminologies utilized in this sector. The potential benefits and drawbacks of various approaches for studying cell biomass or microbial culture broth for the generation of surface-reactive chemicals are also discussed. Additionally, the most popular techniques for detection, structural characterization, and purification of a variety of BS are introduced. A number of straightforward techniques are described in detail, including dialysis, ion exchange, solvent extraction, ultrafiltration, lyophilization, and thin layer chromatography (TLC). In addition to more sophisticated techniques like nuclear magnetic resonance (NMR), fast atom bombardment mass spectroscopy (FAB-MS), gas chromatography-mass spectroscopy (GC-MS), high-pressure liquid chromatography (HPLC), and infrared (IR), proteolysis and sequencing of amino acid are also explained. In this field of study, it is quite necessary to combine several analytical techniques, and it often takes multiple iterations to purify, isolate, and characterize different surface-active substances. The numerous approaches that are essential for researching bio-surfactants are covered in this review.     

Photoinduced surface relief gratings in high-Tg main-chain azoaromatic polymer films

We have synthesized two classes of polyureas with mono- and bisazoaromatic groups in their main chains via reactions between isophorone diisocyanate and the corresponding diamines. Holographic gratings were fabricated on azoaromatic polyurea films prepared by spin-coating from solutions. The effect of high glass transition temperature and dipole moment of azo groups on the formation of gratings was investigated. Although the two polymers have relatively high glass transition temperatures (197 and 236°C), chromophore alignment was induced by laser beam irradiation at modest light intensities. Regularly spaced surface relief gratings on the polymer film were also recorded upon exposure to an interference pattern of two polarized argon laser beams. Erasure could be achieved by heating above T_g or by exposure to one of the beams in a manner similar to low-T_g side-chain azo polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 283–289, 1998     

Induced activity from Cu and SS-304 targets on proton bombardment

Journal of Radioanalytical and Nuclear Chemistry - Presently accelerator facilities emphasizes on generating charged particles with enhanced energy and flux. The radiation protection practices at...