Tania Dey

Background and Aim: There is a growing demand for esthetic dental treatments with composite resins like Ceram.x SpectraTM ST® (CS) due to the importance of a beautiful smile; but color change may occur affecting the longevity and quality of composite restorations. The purpose of this study was to evaluate the color stability ...

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A nanocrystalline TiO₂ glass coating was developed by sintering sol–gel derived thin film at 450°C. FTIR spectroscopy confirmed the absence of hydroxide gel and unreacted precursor as well as the presence of TiO₂. The crystalline phase was predominantly anatase as identified from the XRD measurement and the crystallite size obtained from Scherrer’s equation was 166 nm. This was in good agreement with the TiO₂ nanoparticle size of 148 nm obtained from BET adsorption experiment. The approximate BET surface coverage was 10.38 m²g⁻¹ and the total pore volume was 0.02 cc g⁻¹. Most importantly, the sintered TiO₂ coated quartz glass showed a significant increase of 27.8% in UV reflectance, as obtained from UV-vis measurement and subsequent Kubelka–Munk function. This result is particularly advantageous to prevent bird-strike against high-rise glass buildings and windows.

Sherds of ancient ceramics potteries, dating back to the 7th-century BC and excavated from southern Italy, were analyzed in terms of microstructure and porosity (SEM), elemental composition (EDX), chemical bonding and mineralogical components (FTIR) in order to establish correlation with firing temperature, firing condition and provenance. Si/Al ratio from EDX analysis showed three major categories of raw materials (illite, kaolinite and montmorillonite), suggesting difference in provenance. Uniformly sized silica nanoparticle (0.7 μm diameter) and trace amount of silver is being reported for the first time in one sample. Anorthite mineral and quartz inclusion was detected by FTIR in certain samples. All samples showed a prominent band for Si-O stretching, which shifted from 1062 cm⁻¹, broadened and appeared as doublet, relative to processing temperature. FTIR results proved incomplete dihydroxylation and undissociated carbonate in three samples, indicated a firing temperature of 700–800 C, whereas other samples were fired above 900 °C. Only one sample among these three showed bloating pores in between interconnecting glassy matrix in SEM image, indicating a firing temperature of 1100–1200 °C. Absence of magnetite along with significant Fe and Mn content indicated the formation of jacobsite, an iron manganese spinel complex, MnFe₂O₄, which is responsible for the black gloss effect in two particular samples and can be further confirmed by XRD. Presence of numerous small pores in SEM image of one of these two samples (1.2 μm diameter) was indicative of extended vitrification at higher temperature than the other one. However, magnetite was responsible for black gloss effect in two other samples, proving difference in provenance. Therefore, SEM-EDX and FTIR results can offer valuable insight into the firing conditions, gloss decoration and provenance of ancient ceramic potteries.

Glass surface cleaning is the very first step in advanced coating deposition and it also finds use in conserving museum objects. However, most of the wet chemical methods of glass cleaning use toxic and corrosive chemicals like concentrated sulfuric acid (H₂SO₄), piranha (a mixture of concentrated sulfuric acid and 30% hydrogen peroxide), and hydrogen fluoride (HF). On the other hand, most of the dry cleaning techniques like UV-ozone, plasma, and laser treatment require costly instruments. In this report, five eco-friendly wet chemical methods of glass cleaning were evaluated in terms of contact angle (measured by optical tensiometer), nano-scale surface roughness (measured by atomic force microscopy or AFM), and elemental composition (measured by energy dispersive x-ray spectroscopy or SEM-EDX). These glass cleaning methods are devoid of harsh chemicals and costly equipment, hence can be applied in situ in close proximity with plantation such as greenhouse or upon subtle objects such as museum artifacts. Out of these five methods, three methods are based on the chemical principle of chelation. It was found that the citric acid cleaning method gave the greatest change in contact angle within the hydrophilic regime (14.25° for new glass) indicating effective cleansing and the least surface roughness (0.178 nm for new glass) indicating no corrosive effect. One of the glass sample showed unique features which were traced backed to the history of the glass usage.