1,721,166 research outputs found
The effects of acid and alkaline solutions on cut marks and on the structure of bone: An experimental study on porcine ribs
No full textAmong taphonomical modifications during decomposition processes, little is known about the action of
high or low pH to human tissues and bones. Moreover, acid or basic solutions are seldom used to ease
decomposition and wrecking of the body. In this study a total of 60 samples of porcine bones on which
two cut marks were produced before the beginning of the experiment, were put in six different solutions
with different pH (1, 3, 5, 9, 12, 14) and analyzed every five days over a period of 70 days. Surveys were
carried out macroscopically, with stereomicroscopy and with light microscopy on thin sections. Only the
specimens exposed to extremely acid (12) pH showed evident modifications of the bone’s
structure, as witnessed by the analyses with stereomicroscopy as well. Many samples showed a detachment
of the periosteum; cut marks became soon unrecognizable with pH 14 but still detectable in all the
other samples. The information gained from the present study can be of great help in detecting the exposure
of human tissues to high or low environmental pH and in understanding the effects that these solutions
can exert on human bones
General procedure for the determination of trace amounts of iodine in natural water samples of unknown composition by spectrophotometric titration
No full textIodine in -1 oxidation state is oxidized by iodate, and the titration is monitored spectrophotometrically. Total iodine concentration is obtained by previous reduction. Interferences from oxidizing and reducing substances are eliminated. The reaction is favoured in solution at high chloride concentration. Iodine at very low concentration level (2 10^(-7) M) can be titrated in complex matrices
Extraction and Gas-Chromatographic Determination of Residual Formaldehyde in Microsurgical Materials.
No full textA method for the extraction of residual formaldehyde from surgical materials after sterilisation and its gas
chromatographic determination as the 2,4-dinitrophenylhydrazone derivative is described. Quantitative
determinations are made using 9-cyanoanthracene as an internal standard, instead of anthracene, as
reported previously, because this compound is more stable in solution. The sensitivity is of the order of 10
ng ml-1 of extracted aldehyde. To measure the released formaldehyde under the conditions closest to those
of the human body, because of the purpose of these samples, the formaldehyde was also extracted with a
physiological solution (0.9% NaCI), at 37 "C, with and without stirring
Evaluation of the Activity Coefficients of Some Sulphonated Azo Dyes and of Their Complexes with Metal Ions.
No full textReactions between iodine, iodide and chloride, in aqueous solutions having high ionic strength
No full textThe complexation of iodine with iodide and chloride was investigated by determining the solubility of iodine in different ionic media. The activity coefficients were evaluated on the basis of the specific interaction theory, determining the interaction coefficients of the different charged specie
Structure and medium - dependent photodecomposition of fluoroquinolone antibiotics
No full textThe photochemical reactivity of four fluoroquinolone antibiotics is examined. For norfloxacin (NOR), enoxacin (ENX) and lomefloxacin (LOM), the only process occurring is defluorination (from position 6 for the first two drugs, from position 8 for the last one). The quantum efficiency is both structure and medium dependent (4 close to 0.5 both in water and in 0.1 M phosphate buffer for LOM,- 0.01 for ENX and 0.004 for NOR in buffer, but more than an order of magnitude higher in neat water). Ofloxacin (OFL) is less light sensitive φ 0.001) and undergoes, in part, reactions different from defluorination. The photoreaction involves heterolytic C-F bond fragmentation and its efficiency is determined by the internal charge-transfer character of the excited state (increasing in the series OFL < NOR < ENX < LOM according to the electronegativity of the substituent in position 8) and by the stabilization of the resulting aryl cation (larger for the 8-cation than for the 6-cation). The relevance of these data for the rationalization of the known phototoxicity of these drugs is discussed
Determination of dissolved inorganic species of iodine by spectrophotometric titration
No full textA method for determining iodate and iodine in aqueous solutions is proposed. The assay is similar to a
previously described method for the determination of iodide and iodine, which were titrated with standard
iodate in hydrochloric acid solution. A sample solution made 0.5-1.5 M in hydrochloric acid is titrated with a
standard iodide solution and monitored spectrophotometrically at 230 nm. The species involved have strong
absorbances that are well differentiated at this wavelength. By combining the two titrations it is possible to
resolve any mixture of species of iodine in different oxidation states. The precision of the method (standard
deviation) is the same both when determining a single species (lO3-,I+ ,l2 or I-)a nd a mixture, and is equal to
2 exp -7 M. Chloride and bromide, even at very high concentrations, do not interfere
Analytical application of carbon nanotubes, fullerenes and nanodiamonds in nanomaterials-based chromatographic stationary phases: a review.
No full textAn overview of the most significative results so far attained in the application of carbon nanotubes,fullerenes and anodiamonds as chromatographic separation media is presented. In particular, the authors focus on their use in capillary and packed-column as chromatography, in high performance liquid chromatography and capillary electrochromatography, paying also attention to ecently developed stationary phases for fast chromatography and nanochromatography. The performance of the nanomaterials
is compared to that of planar and amorphous carbon sorbents and critically discussed in regard to retentive capability and selectivity. A wide part of this review is devoted to the most recent improvements achieved in terms of selectivity by use of functionalized nanotubes and by combination of carbon nanotubes with ionic liquids. Practical aspects of synthetic procedures in preparing novel stationary phases in relationship with their chromatographic behaviour are also commented
VOLTAMMETRIC DETERMINATION OF SOME ORGANIC COMPOUNDS OF ARSENIC REDUCED AT THE MERCURY ELECTRODE
No full textCyclic voltammetric scans for methylarsonic acid, dimethylarsinic acid and 3-acetamido-4-hydroxyphenylarsonic acid at amercuryelectrode in an acidic medium show anodic adsorption waves when the starting potential is sufficiently negative; the related arsines are formed on the electrode. Detection limits are at the micromolar level for the absorption peak found at about −0.1 V vs. SCE for all three compounds. Interferences are discussed
Sorption of protons and metal ions from aqueous solutions by a strong base anion-exchange resin loaded with sulphonated azo-dyes
No full textTwo sulphonated azo-dyes, which bear nitrogen donor atoms in the diazo group and are known to complex many heavy metal ions in aqueous solution, have been found to be sorbed by a strong-base anion-exchange resin (Dowex 1-X8) simply by ion-exchange. The resin containing the dyes behaves like a chelating resin, able to sorb copper(II) and nickel(II) from aqueous solution, if proper conditions are chosen. The acidity, ion composition and volume of aqueous solution, and the amount and nature of the sorbed ligand are the factors which determine the fraction of metal ion sorbed when the batch technique is used. The experimental results are interpreted by using a model of resin based on the Donnan equilibrium concept, which allows prediction of the sorption condition on the bases of some independently determined qualities, such as the protonation and complex formation constants in aqueous solution, and the activity of the counter-ion in the resin phase. the exchange of protons between the resin and the aqueous solution can also be explained with this model
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