The hoard of Beçin—non-destructive analysis of the silver coins

We report the results of an analytical investigation on 416 silver-copper coins stemming from the Ottoman Empire (end of 16th and beginning of 17th centuries), using synchrotron micro X-ray fluorescence analysis (SRXRF). In the past, analyses had already been conducted with energy dispersive X-ray fluorescence analysis (EDXRF), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM/EDX) and proton induced X-ray emission spectroscopy (PIXE). With this combination of techniques it was possible to confirm the fineness of the coinage as well as to study the provenance of the alloy used for the coins.     

Laser cleaning of copper roofing sheets subjected to long-lasting environmental corrosion

The study was concerned with the effect of the laser fluence and pulse duration on the microstructure of copper roofing of the Wilanów Palace in Warsaw (Poland) subjected to environmental degradation since the turn 19th century. The techniques used for the microstructure examinations included: SEM+EDS, X-ray diffraction analysis, surface profiling and colour analysis. The measurements of colour of the laser-cleaned surfaces showed that series of 100-μs pulses offer the most effective cleaning. It was also found that by controlling the number of laser pulses it is possible to control the roughness of the cleaned surface.     

Interaction of Candida parapsilosis isolates with human hair and nail surfaces revealed by scanning electron microscopy analysis

Candida parapsilosis is found frequently as commensal organism on epithelial tissues, and is also an increasing cause of nosocomial infection. Scanning electron microscope (SEM) observations were used to analyse the capability of C. parapsilosis cells to adhere and grow as biofilm on human natural substrates and to compare the adherence pattern of isolates exhibiting distinct phenotypes. Cells from the crepe phenotype are predominantly elongated and form pseudohyphae whereas cells from the smooth phenotype are yeast-shaped, either in liquid cultures or on human nail and hair surfaces. The electron micrographs revealed that C. parapsilosis cells from the smooth phenotype adhered in higher number to both surfaces compared to the observed for the crepe phenotype. SEM analysis of human hair surface revealed that cells from the smooth phenotype appear as clumped blastoconidia of uniform morphology embedded in a flocculent extracellular material forming biofilm. The extracellular material and biofilm were seeing in a less extension in the crepe phenotype. A distinct adherence pattern was observed when human nail was used as substrate. Here C. parapsilosis cells seem to be linked to surface structures of human nail plate. Fibrillar extracellular material was observed connecting neighbouring cells as well as nail surface.     

Low voltage TEM: Influences on electron energy loss spectrometry experiments

We discuss the advantages and disadvantages of electron energy loss spectrometry (EELS) a transmission electron microscope (TEM) at different high tensions. Instrumental effects such as energy resolution, spatial resolution, and point spread function of the detecting system, as well as physical effects like inelastic (Coloumb) delocalization and Cerenkov losses are dealt with. It is found that the actually available equipment is suitable for performing low voltage experiments. The energy resolution of a thermo-ionic emitter can be tremendously improved at lower energies, and the detector also has advantageous behaviour.     

Surface texturing of polytetrafluoroethylene by hot embossing

In this study, hot embossing by reusable Ni mold with features in the form of rectangular diffraction gratings of 4 μm period was successfully employed for surface texturing of polytetrafluoroethylene (PTFE) film above the glass transition temperature of PTFE amorphous phase with the aim to enhance surface hydrophobicity. Imprint pressure was set to 0.5 MPa and it was at least tenfold lower than reported by other authors using cold stamping. Embossed gratings were clearly seen on the surface of all imprinted samples even after the annealing at 140 °C and aging for 1 month at room temperature. The best results were achieved when imprint temperature was 150 °C. Measurements of the water contact angle on imprinted PTFE surfaces have showed that increase of the average contact angle for the current test setup was 8°. Using imprint stamp with the more favorable features may lead to somewhat higher hydrophobicity.     

Validation of TPEN as a Zinc Chelator in Fluorescence Probing of Calcium in Cells with the Indicator Fura-2

Fura-2 is widely used as a fluorescent probe to monitor dynamic changes in cytosolic free calcium in cells, where Ca²⁺ can enter through several types of voltage-operated or ligand-gated channels. However, Fura-2 is also sensitive to other metal ions, such as zinc, which may be involved in ionic channels and receptors. There is interest, in particular, in studying the synapses between mossy fibers and CA3 pyramidal cells which contain both calcium and high quantities of free or loosely bound zinc. We have found, through fluorescence probing, that endogenous zinc inhibits mossy fiber calcium transients. However, since these results might be explained by an effect of the zinc chelator N,N,N’,N’-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) on the spectral properties of Fura-2, we have carried out a validation of the method through fluorescence excitation spectra of the complex Fura-2/calcium, and show that TPEN does not affect these spectra. This supports the idea that the observed calcium enhancement is related to a zinc inhibition of presynaptic calcium mechanisms, and confirms the use of the chelator TPEN as a general procedure for the biophysical study of Ca(II) in the presence of Zn(II) using Fura-2.     

Study of Blood Porphyrin Spectral Profile for Diagnosis of Chronic Renal Failure

The progression to end-stage renal failure is independent of the initial pathogenic mechanism. Metabolic acidosis is a common consequence of chronic renal failure that results from inadequate ammonium excretion and decreased tubular bicarbonate reabsorption. Protoporphyrin IX (PpIX) is the immediate metabolic precursor of the heme molecule. The purpose of this study was to evaluate the levels of erythrocytes protoporphyrin IX at an animal model during progressive renal disease. A total of 36 eight-week-old male Wistar rats were divided into six groups: Normal, 4 and 8 weeks after 5/6 nephrectomy (NX). Renal function was evaluated by creatinine clearance and plasma creatinine levels. The autofluorescence of erythrocytes porphyrin of healthy and NX rats was analyzed using fluorescence spectroscopy. Emission spectra were obtained by exciting the samples at 405 nm. Significant differences between normal and NX rats autofluorescence shape occurred in the 600–700 nm spectral region. A correlation was observed between emission band intensity at 635 nm and progression of renal disease.