Nanoconfined Water Clusters in Zinc White Oil Paint

Pigments in oil paint are bound by a complex oil polymer network that is prone to water-related chemical degradation. We use cryo-Fourier-transform infrared spectroscopy and differential scanning calorimetry to study how water distributes inside zinc white oil paint. By measuring water freezing and melting transitions, we show that water-saturated zinc white oil paint contains both liquid-like clustered water and nonclustered water. A comparison of titanium white paint and nonpigmented model systems indicates that water clustering happens near the pigment-polymer interface. The cluster size was estimated in the nanometer range based on the ice melting and freezing temperatures and on the position of the O-D vibration band. As liquid-like water can play a crucial role in the dissolution and transport of ions and molecules, understanding the factors that favor this phenomenon is essential for establishing safe conditions for the conservation of painted works of art.</p

The concentration and origins of carboxylic acid groups in oil paint

Although the concentration of carboxylic acid (COOH) groups is crucial to understand oil paint chemistry, analytical challenges hindered COOH quantification in complex polymerised oil samples thus far. The concentration of COOH groups is important in understanding oil paint degradation because it drives the breakdown of reactive inorganic pigments to dissolve in the oil network and form metal carboxylates. The metal ions in such an ionomeric polymer network can exchange with saturated fatty acids to form crystalline metal soaps (metal complexes of saturated fatty acids), leading to serious problems in many paintings worldwide. We developed two methods based on ATR-FTIR spectroscopy to accurately estimate the COOH concentration in artificially aged oil paint models. Using tailored model systems composed of linseed oil, ZnO and inert filler pigments, these dried oil paints were found to contain one COOH group per triacylglycerol unit. Model systems based on a mixture of long chain alcohols showed that the calculated COOH concentration originates from side chain autoxidation at low relative humidity (RH). The influence of increasing RH and ZnO concentration on COOH formation was studied and high relative humidity conditions were shown to promote the formation of COOH groups. No significant ester hydrolysis was found under the conditions studied. Our results show the potential of quantitative analysis of oil paint model systems for aiding careful (re)evaluation of conservation strategies

Fixed Size of Enlarged Calcified Lymph Nodes in Esophageal Adenocarcinoma despite Complete Remission

Untreated malignant lymph nodes that are calcified are rare. Publications on such calcifications are restricted to case reports. We present a case of calcified lymph nodes in a patient with adenocarcinoma of the gastroesophageal junction that seemed to be nonresponsive to induction chemotherapy, as they did not decrease in size. However, on pathological examination of the resected lymph nodes no vital tumor cells could be detected anymore. Therefore, we hypothesize that a calcified lymph node is unable to shrink, even after adequate remission on induction chemotherapy. This should be taken into account when clinical decision-making depends on the change in size of an enlarged, calcified lymph node as a measure of treatment effect

Toehold-enchanced lna probes for selective pull down and single-molecule analysis of native chromatin

Biological and Soft Matter Physic

Molecular and Serological Intraocular Fluid Analysis of Coxiella burnetii-seropositive Patients with Concurrent Idiopathic Uveitis

Purpose: Previous studies have suggested a link between Q fever and uveitis. We determined whether Coxiella burnetii causes intraocular infection in C. burnetii-seropositive patients with idiopathic uveitis. Methods: From a retrospective observational case series, paired aqueous humor and serum samples from 10 C. burnetii-seropositive patients with idiopathic uveitis were examined for intraocular antibody production by using the Goldmann-Witmer coefficient and by polymerase chain reaction (PCR). Results: Although intraocular IgG against C. burnetii was detected, no intraocular antibody production was observed (low Goldmann Wittmer coefficients). All PCR results were negative. Conclusions: Uveitis due to an intraocular infection with C. burnetii is unlikely