Determination of heavy metals by inductively coupled plasma-optical emission spectrometry in fish from the Piracicaba River in Southern Brazil

A total of 202 fish, representing 16 species, were collected during 2008 (March–October) in the Tanquan region of the Piracicaba River using nets. Flesh samples were collected and analyzed, using inductively coupled plasma-optical emission spectroscopy for Al, As, Cd, Co Cr, Cu, Mn, Mo, Ni, Pb, Se, Sn, Sr, and Zn. The results showed that the flesh of these fish all contained extremely high levels of Al and Sr, and moderately high levels of Cr, As, Zn, Ni, Mn and Pb. The metals were higher in these fish during rainy season, with fish collected during the months of March and October being the highest. In addition, the accumulation of metals was species-dependent. Cascudos (Hypostomus punctatus) and piranhas (Serrasalmus spilopleura) exhibited high levels of almost all of the metals, while curimbata (Prochilodus lineatus) had moderate levels. A few species, including pacu (Piaractus mesopotamicus) and dourado (Salminus maxillosus), had very low levels of most metals. The results show that the Piracicaba River Basin is widely contaminated with high levels of many toxic heavy metals, and that human consumption of some fish species is a human health concern.     

Incorporation of single-walled carbon nanotubes into ferrocene-modified linear polyethylenimine redox polymer films

In this study, we describe the effects of incorporating single-walled carbon nanotubes (SWNTs) into redox polymer-enzyme hydrogels. The hydrogels were constructed by combining the enzyme glucose oxidase with a redox polymer (Fc-C(6)-LPEI) in which ferrocene was attached to linear poly(ethylenimine) by a six-carbon spacer. Incorporation of SWNTs into these films changed their morphology and resulted in a significant increase in the enzymatic response at saturating glucose concentrations (3 mA/cm(2)) as compared to films without SWNTs (0.6 mA/cm(2)). Likewise, the sensitivity at 5 mM glucose was significantly increased in the presence of SWNTs (74 μA/cm(2)·mM) as compared to control films (26 μA/cm(2)·mM). We demonstrate that the increase in the electrochemical and enzymatic response of these films depends on the amount of SWNTs incorporated and the method of SWNT incorporation. Furthermore, we report that the presence of SWNTs in thick films allows for more of the ferrocene redox centers to become accessible. The high current densities of the hydrogels should allow for the construction of miniature biosensors and enzymatic biofuel cells.     

Polysulfonylamines. CXCI. The `almost' polymorphs rac‐trans‐2‐aminocyclohexan‐1‐aminium di(methanesulfonyl)azanide and its 0.11‐hydrate

The title compound, C₆H₁₅N₂⁺·C₂H₆NO₄S₂⁻, crystallizes as a 0.11‐hydrate, (I), in the space group C2; the asymmetric unit consists of two cations (one of each enantiomer), one anion on a general position, two half anions, each with the N atom on a twofold axis, and approximately one fifth of a water molecule. The general anion departs significantly from the usual conformation: it lacks one of the typical `W'‐shaped sequence of O—S—N—S—O atoms. The compound also crystallizes in the solvent‐free form, (II), in the space group P2₁/c, with one formula unit in the asymmetric unit. Both compounds form ribbons of hydrogen‐bonded cation dimers parallel to the b axis. In (I), there are two independent ribbons of opposite chirality, each involving one anion on a special position, and these ribbons are connected by hydrogen bonds to the anion on a general position, resulting in a layer structure parallel to (100). In (II), the chains are connected by hydrogen bonds, and again a layer structure parallel to (100) results.     

A mass spectrometry approach for the study of deglycosylated proteins

Mass spectrometry (MS) analysis, after enzymatic or chemical deglycosylation, requires preparatory steps to remove salts and buffers. In this work, the glycosylated protein fetuin and a lectin protein isolated from the serum of Alligator mississippiensis were used to evaluate methods for desalting samples after an enzymatic or chemical deglycosylation. Precipitation and dialysis were used to prepare the deglycosylated samples for MS analysis. Both the precipitation and dialysis methods were suitable for sample preparation prior to analysis by matrix assisted laser desorption ionization (MALDI) MS.     

Methyl methacrylate-co-itaconic acid (MMA-co-IA) hydrogels for controlled drug delivery

In the present work methyl methacrylate-co-itaconic acid (MMA-co-IA) hydrogels were synthesized by free radical copolymerization of methyl methacrylate (MMA) and itaconic acid (IA) using ethylene glycol dimethacrylate (EGDMA) and methylene bisacrylamide (MBAAm) as crosslinkers and benzoyl peroxide as initiator. Selected samples were loaded with model drug lactulose. For the lactulose release, the effect of pH, monomeric compositions, degree of crosslinking were investigated. The release of lactulose was studied for 8 h period in USP phosphate buffer solutions of varying pH 1.2, 5.5, 6.5 and 7.0. The drug release data were fitted into various kinetics models like the zero order, first order, Higuchi and Peppas. The release kinetics of lactulose from MMA/IA hydrogels was found to be best described by the Peppas model. Results showed that drug release increased by increasing IA content in the hydrogels but the effect of changing of crosslinking ratio on drug release was not significant. The surface morphology of MMA/IA drug loaded hydrogel was studied by SEM which revealed uniform distribution of the drug in the hydrogels. In conclusion, it can be said that lactulose can be successfully incorporated into crosslinked MMA/IA hydrogels and its release can be modulated by changing the mole fraction of the acid component in the gels.     

Flavonoid-DNA binding studies and thermodynamic parameters

Interactional studies of new flavonoid derivatives (Fl) with chicken blood ds.DNA were investigated spectrophotometrically in DMSO-H2O (9:1 v/v) at various temperatures. Spectral parameters suggest considerable binding between the flavonoid derivatives studied and ds.DNA. The binding constant values lie in the enhanced-binding range. Thermodynamic parameters obtained from UV studies also point to strong spontaneous binding of Fl with ds.DNA. Viscometric studies complimented the UV results where a small linear increase in relative viscosity of the DNA solution was observed with added optimal flavonoid concentration. An overall mixed mode of interaction (intercalative plus groove binding) is proposed between DNA and flavonoids. Conclusively, investigated flavonoid derivatives are found to be strong DNA binders and seem to be promising drug candidates like their natural analogues.     

Development and testing of a detailed kinetic mechanism of natural gas combustion in internal combustion engine

A detailed chemical mechanism to describe the combustion of natural gas in internal combustion (IC) engine has been developed,which is consisting of 233 reversible reactions and 79 species.This mechanism accounts for the oxidation of methane,ethane,propane and nitrogen.It has been tested using IC engine model of CHEMKIN 4.1.1 and experimental measurements.The performance of the proposed mechanism was evaluated at various equivalence ratios (φ=0.6 to φ=1.3),initial reactor conditions (Tini=500 to 3500 ℃;Pini...     

Standardization of Biomarkers Gallic Acid and Berberine in Polyherbal Formulation Entoban Capsules by High-Performance Thin-Layer Chromatography—Densitometry

JPC – Journal of Planar Chromatography – Modern TLC - The technological improvement in the structural elucidation of natural compounds has made it probable to generate appropriate...     

Optical and electronic transport anisotropies in plastically deformed CdS

Measurements of polarized optical transmission and reflectivity in the region of the fundamental gap, as well as of the electrical conductivity of plastically deformed CdS were made to probe the electronic properties of this material. From the observed anisotropies in the d.c. electrical conductivity and in optical absorption, a model is suggested to explain the observed features in terms of dislocation energy bands.