Validation of passive samplers for monitoring of acetic and formic acid in museum environments

Acetic acid and formic acid are volatile pollutants leading to degradation of some heritage materials. They are usually determined in museum environments with various types of passive samplers. In this work, SKC UMEx 200 passive samplers, originally intended for sampling of NO2 and SO2, have been validated for sampling of these organic acids. The sampling rates, extraction efficiency, loss through reverse diffusion or during storage, capacity, and detection limits were determined for both acids. For laboratory exposure, a known concentration of both acids was prepared in a flow-through reactor system at controlled temperature and humidity, the samplers were extracted, followed by analysis using ion chromatography. The sampling rates were determined to be 16.7 ml/min for acetic and 17.7 ml/min for formic acid and the detection limits for 7-day exposure were determined to be 2.1μg/m3 for acetic and 1.9μg/m3 for formic acid. The validated method was finally used for sampling of air in two case studies at the National Museum of Slovenia, where the concentrations in the range of 2–54μg/m3 were determined

Spanische Phraseologismen und ihre Verwendung im Text

Die sprachlichen Einheiten, die diese Arbeit zum Thema hat, werden im Alltag üblicherweise als "Redewendungen", "Floskeln" oder "Redensarten" bezeichnet, während die Linguistik diese mitunter sehr unterschiedlichen Phänomene unter dem Begriff der Phraseologie zusammenfasst. Als wichtiger Bestandteil jeder natürlichen Sprache sind Phraseologismen in verschiedensten Kontexten unentbehrlich. In meiner Arbeit interessiere ich mich für die Phraseologie im tatsächlichen Gebrauch. Anhand von redaktionellen Artikeln und User-Kommentaren auf der Webseite der spanischen Sportzeitung "Marca" zeige ich auf, welche Arten von Phraseologismen in welchen Situationen verwendet werden und was den besonderen Reiz dieser sprachlichen Fertigbausteine ausmacht

Use of genetic algorithms with multivariate regression for determination of gelatine in historic papers based on FT-IR and NIR spectral data

Quantitative non-destructive analysis of individual constituents of historic rag paper is crucial for its effective preservation. In this work, we examine the potentials of mid- and near-infrared spectroscopy, however, in order to fully utilise the selectivity inherent to spectroscopic multivariate measurements, genetic algorithms were used to select spectral data derived from information-rich FT-IR or UV-vis-NIR measurements to build multivariate calibration models based on partial least squares regression, relating spectra to gelatine content in paper. A selective but laborious chromatographic method for the quantification of hydroxyproline (HYP) has been developed to provide the reference data on gelatine content. We used 9-fluorenylmethyl chloroformate (FMOC) to derivatise HYP, which was subsequently determined using reverse-phase liquid chromatographic separation and fluorimetric detection. In this process, the sample is consumed, which is why the method can only be used as a reference method.The sampling flexibility afforded by small-size field-portable spectroscopic instrumentation combined with chemometric data analysis, represents an attractive addition to existing analytical techniques for cultural heritage materials. (C) 2010 Elsevier B.V. All rights reserved

The effect of particulate matter on paper degradation

Background: In this work we explore the chemical effects of particulate matter on paper. We exposed paper made of pure cellulose to the environment in different locations in central London, outdoors (in sheltered conditions) and indoors, for a period of up to 6 months. We monitored particulate matter (PM) deposition by counting the particles deposited every month with a scanning electron microscope. We analysed elemental composition of the deposited particles using inductively coupled plasma mass spectrometry. After accelerated degradation of the exposed samples, we determined the degree of polymerisation using viscometry. Results: We observed higher deposition rates and higher metal concentration outdoors than indoors. Elemental analysis of the deposited particles revealed the presence of some transition metals (Fe, Cu, Cr) that can contribute to the degradation of cellulose fibres through the Fenton reaction. By comparing the degree of polymerisation of pro‑ tected, unprotected and unexposed samples we could determine the relative contribution of PM deposition on the increase of the degradation rate. We found that the surface concentration of iron correlates with the reduction in the degree of polymerisation of the exposed paper. Conclusions: The results suggest that the presence of Fenton metals in PM has a significant effect on the accelera‑ tion of the degradation of cellulose. However, we estimate that this will unlikely occur at the levels of area coverage by PM that are typically avoided in indoor heritage through preventive maintenance and cleaning

A study of degradation of historic parchment using small-angle X-ray scattering, synchrotron-IR and multivariate data analysis

Parchment has been in use for thousands of years and has been used as the writing or drawing support for many important historic works. A variety of analytical techniques is currently used for routine assessment of the degree of denaturation of historic parchment; however, because parchment has a heterogeneous nature, analytical methods with high spatial resolution are desirable. In this work, the use of small-angle X-ray scattering (SAXS) and synchrotron-IR (SR-IR) was examined in conjunction with multivariate data analysis to study degradation of an extended set of historic parchment samples, and particularly to investigate the effect of lipids and the presence of iron gall ink on the degradation processes. In the data analysis, shrinkage temperature, lipid content, sample age, presence of ink and accelerated degradation were included. The analysis of loading factors in partial least-squares regression and principal component analyses based on SAXS, SR-IR and other analytical and descriptive data reveals the effect of lipid removal on diffraction patterns, and lipids are found to cause the degradation process in parchment to accelerate. The effect of iron gall ink is also evident, although the mechanism of ageing is different to that of natural ageing in the absence of ink. In addition, a historic parchment score from ca. 1750 is examined, demonstrating the significant effect of iron gall ink, and lipids and inorganic soiling on its increased degradation. © 2011 Springer-Verlag

Falstatin, a Cysteine Protease Inhibitor of Plasmodium falciparum, Facilitates Erythrocyte Invasion

Erythrocytic malaria parasites utilize proteases for a number of cellular processes, including hydrolysis of hemoglobin, rupture of erythrocytes by mature schizonts, and subsequent invasion of erythrocytes by free merozoites. However, mechanisms used by malaria parasites to control protease activity have not been established. We report here the identification of an endogenous cysteine protease inhibitor of Plasmodium falciparum, falstatin, based on modest homology with the Trypanosoma cruzi cysteine protease inhibitor chagasin. Falstatin, expressed in Escherichia coli, was a potent reversible inhibitor of the P. falciparum cysteine proteases falcipain-2 and falcipain-3, as well as other parasite- and nonparasite-derived cysteine proteases, but it was a relatively weak inhibitor of the P. falciparum cysteine proteases falcipain-1 and dipeptidyl aminopeptidase 1. Falstatin is present in schizonts, merozoites, and rings, but not in trophozoites, the stage at which the cysteine protease activity of P. falciparum is maximal. Falstatin localizes to the periphery of rings and early schizonts, is diffusely expressed in late schizonts and merozoites, and is released upon the rupture of mature schizonts. Treatment of late schizionts with antibodies that blocked the inhibitory activity of falstatin against native and recombinant falcipain-2 and falcipain-3 dose-dependently decreased the subsequent invasion of erythrocytes by merozoites. These results suggest that P. falciparum requires expression of falstatin to limit proteolysis by certain host or parasite cysteine proteases during erythrocyte invasion. This mechanism of regulation of proteolysis suggests new strategies for the development of antimalarial agents that specifically disrupt erythrocyte invasion

Therapeutic targeting of cathepsin C::from pathophysiology to treatment

Cathepsin C (CatC) is a highly conserved tetrameric lysosomal cysteine dipeptidyl aminopeptidase. The best characterized physiological function of CatC is the activation of pro-inflammatory granule-associated serine proteases. These proteases are synthesized as inactive zymogens containing an N-terminal pro-dipeptide, which maintains the zymogen in its inactive conformation and prevents premature activation, which is potentially toxic to the cell. The activation of serine protease zymogens occurs through cleavage of the N-terminal dipeptide by CatC during cell maturation in the bone marrow. In vivo data suggest that pharmacological inhibition of pro-inflammatory serine proteases would suppress or attenuate deleterious effects of inflammatory/auto-immune disorders mediated by these proteases. The pathological deficiency in CatC is associated with Papillon-Lefèvre syndrome. The patients however do not present marked immunodeficiency despite the absence of active serine proteases in immune defense cells. Hence, the transitory pharmacological blockade of CatC activity in the precursor cells of the bone marrow may represent an attractive therapeutic strategy to regulate activity of serine proteases in inflammatory and immunologic conditions. A variety of CatC inhibitors have been developed both by pharmaceutical companies and academic investigators, some of which are currently being employed and evaluated in preclinical/clinical trials