PURPOSETranslucency and colour stability are two most important aspects for an aesthetic dental restoration. Glass ceramic restorations are popular amongst clinicians because of their superior aesthetic properties. In the last decade, zirconia has generated tremendous interest due to its favorable mechanical and biological properties. However, zirconia lacks the translucency that lithium disilicate materials possess and therefore has limitations in its use, especially in esthetically demanding situations. There has been a great thrust in research towards developing translucent zirconia materials for dental restorations. The objective of the study was to evaluate and compare the transmittance of a translucent variant of zirconia to lithium disilicate.MATERIALS AND METHODSTwo commercially available zirconia materials (conventional and high translucency) and 2 lithium disilicate materials (conventional and high translucency) with standardized dimensions were fabricated. Transmittance values were measured for all samples followed by a microstructural analysis using a finite element scanning electron microscope. One way analysis of variance combined with a Tukey-post hoc test was used to analyze the data obtained (P=.05).RESULTSHigh translucency lithium disilicate showed highest transmittance of all materials studied, followed by conventional lithium disilicate, high translucency zirconia and conventional zirconia. The difference between all groups of materials was statistically significant. The transmittance of the different materials correlated to their microstructure analysis.CONCLUSIONDespite manufacturers' efforts to make zirconia significantly more translucent, the transmittance values of these materials still do not match conventional lithium disilicate. More research is required on zirconia towards making the material more translucent for its potential use as esthetic monolithic restoration.

Highly dispersed nanometer-sized a-Fe 2 O 3 (hematite) and c-Fe 2 O 3 (maghemite) iron oxide particles were synthesized by the combustion method. Ferric nitrate was used as a precursor. Xray diffractometer study revealed the phase purity of aand c-Fe 2 O 3 . Both the products were characterized using field emission scanning electron microscope and transmission electron microscope for particle size and morphology. Necked structure particle morphology was observed for the first time in both the iron oxides. The particle size was observed in the range of 25-55 nm. Photodecomposition of H 2 S for hydrogen generation was performed using aand c-Fe 2 O 3 . Good photocatalytic activity was obtained using aand c-Fe 2 O 3 as photocatalysts under visible light irradiation. P. Gouma-contributing editor

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The simple, template-free, low-temperature, large-scale synthesis of nanostructured CdS with the hexagonal wurtzite phase from bulk cadmium oxide under solid-phase conditions is demonstrated for the first time. The novel approach involves the homogenization of cadmium oxide (CdO) and thiourea in various stoichiometric ratios at moderate temperature. Among the different molar ratios of CdO and thiourea studied, the CdO/NH(2) CSNH(2) molar ratio of 1:2 is found to be the best to obtain highly pure CdS. The obtained CdS nanostructures exhibit excellent cubic morphology and high specific surface area with a particle size in the range of 5-7 nm. The bandgap of the nanostructured CdS is in the range of 2.42 to 2.46 eV due to its nanocrystalline nature. In photoluminescence studies, emission is observed at 520.34 and 536.42 nm, which is characteristic of the greenish-yellow region of the visible spectrum. Considering the bandgap of the CdS is within the visible region, the photocatalytic activity for H(2) generation and organic dye degradation are performed under visible-light irradiation. The maximum H(2) evolution of 2945 μmol h(-1) is obtained using nanostructured CdS prepared in the 1:2 ratio, which is three times higher than that of bulk CdS (1010 μmol h(-1) ). CdS synthesized using the 1:2 molar ratio shows maximum methylene blue degradation (87.5%) over a period of 60 min, which is approximately four times higher than that of bulk CdS (22%). This amazing performance of the material is due to its nanocrystalline nature and the high surface area of the CdS. The proposed simple methodology is believed to be a significant breakthrough in the field of nanotechnology, and the method can be further generalized as a rational preparation scheme for the large-scale synthesis of various other nanostructured metal sulfides.

Polymorphous low-grade adenocarcinoma (PLGA) is difficult to diagnose due to its indolent clinical presentation and due to its morphological diversity that includes several microscopic patterns. Distinguishing it from high-grade tumors of salivary gland is important, as the management and prognosis of this tumor differ. We report a considerably rare case of PLGA in retromolar area highlighting various diagnostic challenges caused by the overlap of clinical and microscopic features between PLGA and other salivary gland neoplasms and discuss current management strategies.

It is renowned that the oil refineries are venting off 15-20% H 2 S and hardly 5% has been utilized to produce sulphur and water ubiquitously by the Claus process. This process is un-economical, highly polluting and by-products create further acute environmental problems. Here, we have demonstrated the significant approach of the conversion of poisonous H 2 S into H 2 by stable orthorhombic QD-CdS-glass nanosystems using a most abundant solar light energy source. This is an eco-friendly process that produces cheaper hydrogen as well as degrades organic dyes efficiently. We have investigated a novel, Q-CdS (highly mono-dispersed) germanate glass nanocomposite. Surprisingly, the CdS quantum dots (QDs) obtained in the glass matrix are orthorhombic in structure and highly thermally stable. Generally, the orthorhombic CdS powder is in a metastable state i.e. unstable at normal conditions. The quantum dots of 4-14 nm size of CdS were grown for the first time in the germanate glass. The confinement of orthorhombic CdS was studied using UV-Vis spectroscopy and photoluminescence. There is a drastic change in the band gap of glass without CdS nanocrystals (3.16 eV) as compared to the glass with orthorhombic CdS QDs (2.25 eV). Considering the suitable band gap of the CdS quantum dot-glass for the visible light absorption, the studies of the photocatalytic activity for H 2 generation and dye degradation was performed under visible light irradiation for the first time. High H 2 evolution, i.e. 3780 μmol h −1 , was obtained, which is much higher than earlier reported for CdS nano-powder. More significantly, the catalyst is stable and easily regenerated as compared to other normal catalysts. The glass nanocomposite also showed excellent methylene blue degradation under visible light irradiation. Such orthorhombic QD-CdS-glass nanocomposites have great significance because they have potential applications in solar cell, LED and other optoelectronic devices.

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