The biodeterioration of synthetic resins used in conservation

Synthetic resins have been extensively employed by artists in their works of art, e.g. as paint binders, or by conservators for conservation treatments, e.g. as stone consolidants and protectives. It is generally thought that synthetic resins are less prone to chemical, physical and biological deterioration than other organic products but there are many articles in the scientific literature and some reports in the conservation of cultural heritage literature claiming that microorganisms are capable of degrading synthetic resins. This paper reviews the researches on the biodeterioration of synthetic resins used in the conservation of cultural heritage, including stone, painting and textile materials, carried out in the last fifty years.     

Oxidation of phosphorus compounds by Fenton's reagent

In the present work a Fenton's treatment for the oxidation of a phosphorous compounds mixture, simulating a match manufacturing industry wastewater, were studied. Experimental tests were performed on three sample solutions at a phosphorus concentration of 250, 500 and 750 mg/l. In each solution an equal amount of sodium phosphite and sodium hypophosphite was dissolved. The investigation of pH, temperature and reagents ratio on the oxidation rate led to the individuation of the optimal process operating conditions. The results show that Fenton's reagent provides a powerful conversion to phosphate of the phosphorous solution. In particular at pH=3.5 and 20 degrees C a residual concentration of non oxidized phosphorus in compliance with the Italian regulation limits for industrial wastewater disposal. Tests performed on sample solution of 500 mg/l P and 750 mg/l P by adding hydrogen peroxide and bivalent iron in three sequential steps led to similar reaction efficiencies to tests carried out adding both Fenton's reagents in one step, but with a remarkably lower reagents consumption.     

Hyperfine characterization of tin-doped indium sesquioxide

The hyperfine interactions at In and Sn sites of In₂O₃Sn (ITO) were measured through time-differential perturbed angular correlations and Mössbauer spectroscopy, respectively. Polycrystalline samples prepared by co-precipitation with nominal 0.025, 1 and 5 at.% Sn were studied. They all showed the cubic bixbyite structure characteristic of In₂O₃ after annealings at 200 °C. The quadrupole interaction at In sites appears nearly independent of Sn concentration being the main result of the presence of Sn in the lattice, the gradual disappearence of the dynamic perturbation caused by after-effects. The Mössbauer data demonstrate that Sn ions are in a 4+ state with Q=0.60₆ mm/s and=0.22₆ mm/s relative to SnO₃Ca at room temperature.     

Quantitative polymerase chain reaction and microchip electrophoresis to detect major rearrangements of the low-density lipoprotein receptor gene causing familial hypercholesterolemia

A variety of rearrangements in the low-density lipoprotein receptor (LDLR) gene cause severe forms of familial hypercholesterolemia (FH). However, current methods for searching these abnormalities in FH samples, e.g., Southern and Northern Blot, are labor-intensive and not routinely used by diagnostic laboratories. We developed a simpler approach based on the quantitative polymerase chain reaction (PCR) amplification of part or all gene's coding sequences by a series of multiplex amplifications comprising three nonadjacent gene sections plus a fourth section used as an internal reference. Thereafter, the analysis of these PCR products by microchip electrophoresis revealed either deletions or duplications in the investigated gene sections through the simple comparison of electropherograms obtained from mutant and control samples. This required primers leading to well-resolved peaks with minimal size differences among coamplified products and PCR conditions allowing a linear quantitative response to template amount variations as those caused by duplication or deletion of specific gene sections. Also, the inclusion of exon 17 amplification product as an internal reference in each multiplex PCR allowed the normalization of quantitative results by dividing the area of each amplified section by the area of exon 17. The comparison of these ratios calculated from 10 carriers of 6 LDLR known rearrangements with those obtained from 14 control samples showed that gross deletions roughly halved and duplications doubled the ratio values of exons involved in the mutation. This allowed to distinguish gross mutations from sample-to-sample differences that reached at maximum 8% variation over mean values.     

HPLC‐ESI‐MS analysis of oral human fluids reveals that gingival crevicular fluid is the main source of oral thymosins β4 and β10

Thymosin β₄ (Tβ₄), its sulfoxide, and thymosin β₁₀ (Tβ₁₀) were detected in human saliva and identified by different strategies based on RP HPLC coupled to electrospray multidimensional IT MS. Tβ₄ was almost always detected in whole saliva, its sulfoxide sporadically, Tβ₁₀ rarely. Tβ₄ was undetectable in parotid saliva and less concentrated in submandibular/sublingual saliva than in whole saliva. Analysis of gingival crevicular fluid revealed high relative amounts of Tβ₄, Tβ₄ sulfoxide, and Tβ₁₀ in all the samples. Tβ₄ mean concentration was 200 times higher in crevicular fluid (20 μmol/L, N = 9) than in whole saliva (0.1 μmol/L, N = 9). Crevicular fluid concentration of Tβ₄ (ca. 5% represented by its sulfoxide) and β₁₀ significantly correlated (r = 0.856; N = 9), and their ratio was about 5. A significant correlation was also observed between Tβ₄ concentrations in whole saliva and gingival crevicular fluid (r = 0.738; N = 9). Immunohistochemical analysis of the major salivary glands showed that immunoreactivity for Tβ₄ is restricted to ductal cells, with minor degree of focal positivity in some acinar cells. On the whole, results indicate that gingival sulcus is a main, although not the sole, source for oral Tβ₄ and Tβ₁₀.     

Isoelectric Focusing with Immobilized pH Gradients

Abstract

The technique of isoelectric focusing (IEF) via immobilized pH gradients (IPG) was first announced to the scientific community at a meeting of the International Electrophoresis Society in Athens, April 1982, as the result of an intensive collaborative effort [1]. In five years, the technique has been extensively developed in three fundamental aspects: analytical, preparative and as a first dimension of two-dimensional (2-D) maps. The merits and, recently, the flaws of the IPG technique have been evaluated and recognized, so that at the present writing we feel it is ready for successful introduction in most life-science laboratories.