Analysis on Material Characteristics of Restored Areas with Mortar and Basis of Surface Deterioration on the Stupa of State Preceptor Jigwang from Beopchensaji Temple Site in Wonju, Korea

The Stupa of State Preceptor Jigwang from Beopcheonsa Temple Site in Wonju (National Treasure) is a representative stupa of the Goryeo Dynasty, with outstanding Buddhist carvings and splendid patterns, clearly indicating its honoree and year of construction. However, it was destroyed by bombing during the Korean War (1950-1953) and repaired and restored with cement and reinforcing bars in 1957. The surface condition of the original stone shows long-term deterioration due to the m ortar used in past restorations. In order to identify the exact causes of deterioration, the m ortar and surface contaminants on the original stone were analyzed. Portlandite, calcite, ettringite, and gypsum from the mortar were identified, and its ongoing deterioration was observed through pH measurements and the neutralization reaction test. Analysis of surface contaminants identified calcite and gypsum, both poorly water-soluble substances, and their growth in volume among rock-forming minerals was observed by microscopy. Based on those results, semi-quantitative analysis of Ca and S contents significantly influencing the formation of salt crystals was conducted using P-XRF to analyze the basis of surface deterioration, and cross-validation was performed by comparing the body stone affected by the mortar and the upper stylobate stone unaffected by the mortar. Results indicate that the elements are directly involved in the surface deterioration of the body stone.

Mixed Cation Halide Perovskite under Environmental and Physical Stress

Despite the ideal performance demonstrated by mixed perovskite materials when used as active layers in photovoltaic devices, the factor which still hampers their use in real life remains the poor stability of their physico-chemical and functional properties when submitted to prolonged permanence in atmosphere, exposure to light and/or to moderately high temperature. We used high resolution photoelectron spectroscopy to compare the chemical state of triple cation, double halide Csx(FA0.83MA0.17)(1−x)Pb(I0.83Br0.17)3 perovskite thin films being freshly deposited or kept for one month in the dark or in the light in environmental conditions. Important deviations from the nominal composition were found in the samples aged in the dark, which, however, did not show evident signs of oxidation and basically preserved their own electronic structures. Ageing in the light determined a dramatic material deterioration with heavily perturbed chemical composition also due to reactions of the perovskite components with surface contaminants, promoted by the exposure to visible radiation. We also investigated the implications that 2D MXene flakes, recently identified as effective perovskite additive to improve solar cell efficiency, might have on the labile resilience of the material to external agents. Our results exclude any deleterious MXene influence on the perovskite stability and, actually, might evidence a mild stabilizing effect for the fresh samples, which, if doped, exhibited a lower deviation from the expected stoichiometry with respect to the undoped sample. The evolution of the undoped perovskites under thermal stress was studied by heating the samples in UHV while monitoring in real time, simultaneously, the behaviour of four representative material elements. Moreover, we could reveal the occurrence of fast changes induced in the fresh material by the photon beam as well as the enhanced decomposition triggered by the concurrent X-ray irradiation and thermal heating.

Atmospheric plasma jet device for versatile electron microscope grid treatment

Atmospheric pressure plasmas have been widely applied in surface modification and biomedical treatment due to its ability to generate highly reactive radicals and charged particles. In cryogenic electron microscopy (cryo-EM), plasmas have been used in eliminating the surface contaminants as well as generating the hydrophilic surface to embed the specimen on grids. Particularly, plasma treatment is a prerequisite for negative stain and quantifoil grids,which are coated with hydrophobic carbon on the grid surface. Here we introduce a nonthermal atmospheric plasma jet system as an alternative new tool for surface treatment. Unlike the conventional glow discharger, we found that the plasma jet system successfully cleans the grid surface and introduces hydrophilicity on grids in the ambient environment without introducing a vacuum. Therefore, we anticipate the plasma jet system will be beneficial in many aspects, such as cost-effective, convenient, versatile, and potential applications in surface modification for both negative stain and cryo-EM grid treatment.

Comparative Study of NAP-XPS and Cryo-XPS for the Investigation of Surface Chemistry of the Bacterial Cell-Envelope

Bacteria generally interact with the environment via processes involving their cell-envelope. Thus, techniques that may shed light on their surface chemistry are attractive tools for providing an understanding of bacterial interactions. One of these tools is Al Kα-excited photoelectron spectroscopy (XPS) with its estimated information depth of <10 nm. XPS-analyses of bacteria have been performed for several decades on freeze-dried specimens in order to be compatible with the vacuum in the analysis chamber of the spectrometer. A limitation of these studies has been that the freeze-drying method may collapse cell structure as well as introduce surface contaminants. However, recent developments in XPS allow for analysis of biological samples at near ambient pressure (NAP-XPS) or as frozen hydrated specimens (cryo-XPS) in vacuum. In this work, we have analyzed bacterial samples from a reference strain of the Gram-negative bacterium Pseudomonas fluorescens using both techniques. We compare the results obtained and, in general, observe good agreement between the two techniques. Furthermore, we discuss advantages and disadvantages with the two analysis approaches and the output data they provide. XPS reference data from the bacterial strain are provided, and we propose that planktonic cells of this strain (DSM 50090) are used as a reference material for surface chemical analysis of bacterial systems.

Instant Antibacterial and Anti-Inflammatory Osmotic Polymeric Film to Treat Sore Throat in Children

Background: Pharyngitis, a common viral throat infection in children, involving inflammation, widespread local bacterial contamination and tissue destruction. When clinical signs appear, the disease already became multifactorial. In the absence of any multitarget treatment, we conceived a new generation of topical, osmotic, anti-inflammatory, throat surface cleaning polymeric film, capable of detaching and draining throat surface contaminants nearly instantly. Material and methods: A glycerol and polymer containing osmotic film was prepared. Osmotic film attracts hypotonic liquid from the throat tissue, which detach and drain throat surface contaminants and create a favorable environment for cell growth and healing. Specific pro-inflammatory cytokine and virus glycoprotein binding polymers were incorporated in the film to suppress the inflammation. An observational, randomized, placebo-controlled study was performed after the approval of ethical committee on 30 children aged between (3-15), presenting symptoms of acute pharyngitis. After randomization, test product (n=20) and saline control (n=10) solutions were applied as 3-4 throat sprays 4-5 times / day for 15-days. Change in all the key pharyngitis symptom (difficulty swallowing, throat inflammation, irritation, redness, and bacterial deposit) were evaluated employing two-tailed Student’s test for followed by the post hoc Bonferroni’s test for comparisons of multiple groups Results: Only a few specific polymers were able to bind with viral proteins and/or cytokines in adequate filmogen concentrations. Throat surface cleaning and cytokine neutralization strongly decrease all the pharyngitis symptoms and need for antibiotic therapy compared to controls (p<0.05 from day 3 onwards). No adverse effects were noted in any of the groups. Conclusion: Clinical results showed excellent efficacy and safety of osmotically active polymeric film. Polymeric drugs may represent an excellent multitarget treatment approach to minimize the use of antibiotics and chemical drugs in the future.

Surface chemistry of structural materials subjected to corrosion

The article describes a comprehensive mass spectrometric approach to the study of surfaces of structural materials. The combined use of thermal desorption mass spectrometry, gas and liquid chromatography, and laser desorption/ionization mass spectrometry (LDI) to provide information about the surface and surface layers of materials is proposed. The suggested method allows one to determine the thermodynamic characteristics of compounds and surface contaminants adsorbed on surfaces, as well as surface layers, to determine the composition of volatile and non-volatile contaminants on the surface, and to determine the nature of the distribution over the surface of these compounds. The method allows to obtain the most complete information about the surface condition and can be used to predict the life of structural materials.