Abstract: Most computer XRF-spectrum deconvolution routines make use of fixed intensity ratios for the lines from one element. The magnitude of the error that fixed ratios imply has been quantitatively evaluated for samples with a varible thickness or matrix. A procedure for routinely adapting the line ratios according to the matrix effect in every sample (by making use of the matrix information present in the scatter peaks) enhances the accuracy of the spectrum evaluation.

Abstract: There is a type of filament that forms dosed contours encircling regions of one polarity of magnetic field, while the surrounding region has the opposite polarity One distribution of ring-filaments has sizes 2R = 40,000 to 160,000 km with the maximum around 100,000 km; the other distribution (with filaments and filament channels) has bigger sizes, with a maximum around 300,000 km. At low and mid latitudes the radial component B-rs (radial for the Sun) in the region outlined by filaments varies from 50 to 100 gauss, while the longitudinal component B-phi varies from 10 to 30 gauss. The total current inside the filament is 10(10) – 10(11) A, the ratio R/a approximate to 5 to 10, the magnetic flux crossing the surface is approximate to 10(21) – 10(22) MX; th, magnetic energy is approximate to 10(29) – 10(31) erg. Polar ring-filaments at latitudes 60 degrees-80 degrees are related to the polar magnetic field reversal and the quasi-flare processes at the poles during the field reversal. Correlation between B-rs and B-phi for the polar filament bands cannot be satisfactorily explained. A theoretical model using the conservation laws is used to study the relations between the various fields, currents, etc, of shrinking polar ring-filaments and their evolution. According to this theory ring-filaments should rise higher above the photosphere when shrinking. However, observations show that the height lowers. Presumably the discrepancy is due to the lack of dissipation in the model.

Abstract: Samples of cretaceous limestone have been treated with three application methods (poultice, immersion and brushing) using different concentrations of ammonium oxalate solution (AmOx) and varying treatment time in order to test the efficiency of surface and in-depth formation of a protective layer of calcium oxalate (CaOx). Synchrotron-based microanalytical techniques (SR-mu XRD with 12.5 mu mx7.5 mu m (HxV) probe size, SR-mu FTIR with 10 mu mx10 mu m and 8 mu mx20 mu m probe sizes) and laboratory mu FTIR, XRD and SEM have been employed for analysis of the treated samples. Synchrotron-based techniques showed variations in the CaOx distribution along the surface on a micrometer scale. All treatments resulted in the development of a CaOx layer with a maximum thickness of approximately 40 mu m. Application by the brushing method with 10 1-min applications with 5-min breaks during one hour showed a development of the calcium oxalate layer equivalent to the poultice treatment taking 10 h. This treatment could be preferred for large marble or limestone surfaces where poultice usage is economically not feasible.

Abstract: Since cleaning of artworks may cause undesirable physicochemical alterations and is a nonreversible procedure, it is mandatory to adopt the proper cleaning procedure. Such a procedure should remove undesired materials whilst preserving the original surface. In this regard, numerous gels have been developed and exploited for the cleaning of various artwork surfaces. Lately, agarose (AG) and polyvinyl alcohol-borax (PVA-B) hydrogels have been widely employed as cleaning tools by conservators. Both hydrogels show some limitations in specific cleaning practices. In this work, we investigated the influence of including increased levels of agarose into PVA-B systems. For this reason, we performed a detailed characterization on the double network (DN) hydrogel including the chemical structure, the liquid phase retention, the rheological behavior, and the self-healing behavior of various PVA-B/AG double network hydrogels. These new hydrogels revealed better properties than PVA-B hydrogels and obviated their limitations. The inclusion of AG into PVA-B systems enhanced the liquid retention capacity, shape-stability, and mechanical strength of the blend. Furthermore, AG minimized the expelling/syneresis issue that occurs when loading PVA-B systems with low polarity solvents or chelating agents. The resultant double network hydrogel exhibits relevant self-healing properties. The PVA-B/AG double network is a new and useful cleaning tool that can be added to the conservators' tool-kit. It is ideal for cleaning procedures dealing with porous and complex structured surfaces, vertical surfaces and for long time applications.

Abstract: Background: It has been hypothesized that ambient particulate air pollution is able to modify the autonomic nervous control of the heart, measured as heart rate variability (HRV) . Previously we reported heterogeneous associations between particulate matter with aerodynamic diameter < 2.5 µm (PM2.5) and HRV across three study centers. Objective: We evaluated whether exposure misclassification, effect modification by medication, or differences in particle composition could explain the inconsistencies. Methods: Subjects with coronary heart disease visited clinics biweekly in Amsterdam, the Netherlands ; Erfurt, Germany ; and Helsinki, Finland for 68 months. The standard deviation (SD) of NN intervals on an electrocardiogram (ECG ; SDNN) and high frequency (HF) power of HRV was measured with ambulatory ECG during paced breathing. Outdoor levels of PM2.5 were measured at a central site. In Amsterdam and Helsinki, indoor and personal PM2.5 were measured during the 24 hr preceding the clinic visit. PM2.5 was apportioned between sources using principal component analyses. We analyzed associations of indoor/personal PM2.5, elements of PM2.5, and source-specific PM2.5 with HRV using linear regression. Results: Indoor and personal PM2.5 were not associated with HRV. Increased outdoor PM2.5 was associated with decreased SDNN and HF at lags of 2 and 3 days only among persons not using beta-blocker medication. Traffic-related PM2.5 was associated with decreased SDNN, and long-range transported PM2.5 with decreased SDNN and HF, most strongly among persons not using beta blockers. Indicators for PM2.5 from traffic and long-range transport were also associated with decreased HRV. Conclusions: Our results suggest that differences in the composition of particles, beta-blocker use, and obesity of study subjects may explain some inconsistencies among previous studies on HRV.

Abstract: Airborne particulate matter (PM) includes semi-volatile organic compounds (SVOCs), which can be deposited on vegetation matrices such as plant leaves. In alternative to air-point measurements or artificial passive substrates, leaf monitoring offers a cost-effective, time-integrating means of assessing local air quality. In this study, leaf washing solutions from ivy (Hedera hibernica) leaves exposed during one-month at different land use classes were explored via comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-TOFMS). The composition of leaf-deposited SVOCs, corrected for those of unexposed leaves, was compared against routinely monitored pollutants concentrations (PM10, PM2.5, O3, NO2, SO2) measured at co-located air monitoring stations. The first study on leaf-deposited SVOCs retrieved from washing solutions, herein reported, delivered a total of 911 detected compounds. While no significant land use (rural, urban, industrial, traffic, mixed) effects were observed, increasing exposure time (from one to 28 days) resulted in a higher number and diversity of SVOCs, suggesting cumulative time-integration to be more relevant than local source variations between sites. After one day, leaf-deposited SVOCs were mainly due to alcohols, N-containing compounds, carboxylic acids, esters and lactones, while ketones, diketones and hydrocarbons compounds gained relevance after one week, and phenol compounds after one month. As leaf-deposited SVOCs became overall more oxidized throughout exposure time, SVOCs transformation or degradation at the leaf surface is suggested to be an important phenomenon. This study confirmed the applicability of GCxGC-TOFMS to analyze SVOCs from leaf washing solutions, further research should include validation of the methodology and comparison with atmospheric organic pollutants.

Abstract: In this article we investigate the possibility of scaling down enzyme-gelatin modified electrodes by spin coating the enzyme-gelatin layer. Special attention is given to the electrochemical behavior of the selected enzymes inside the gelatin matrix. A glassy carbon electrode was used as a substrate to immobilize, in the first instance, horse heart cytochrome c (HHC) in a gelatin matrix. Both a drop dried and a spin coated layer was prepared. On scaling down, a transition from diffusion controlled reactions towards adsorption controlled reactions is observed. Compared to a drop dried electrode, a spin coated electrode showed a more stable electrochemical behavior. Next to HHC, we also incorporated catalase in a spin coated gelatin matrix immobilized on a glassy carbon electrode. By spincoating, highly uniform sub micrometer layers of biocompatible matrices can be constructed. A full electrochemical study and characterization of the modified surfaces has been carried out. It was clear that in the case of catalase, gluteraldehyde addition was needed to prevent leaking of the catalase from the gelatin matrix.