Er:YAG Laser and Fractured Incisor Restorations: An In Vitro

Introduction. The aim of this study was to analyse the effects of an Er:YAG laser on enamel and dentine in cases of dental restorations involving fractured teeth, utilizing the dental fragment. Materials and Methods. Seventy-two freshly extracted bovine incisors were fractured at the coronal level by using a hammer applied with a standardized method, and the fragment was reattached by using three different methods: Er:YAG laser, orthophosphoric acid, and laser plus acid. The different groups were evaluated by a test realized with the dynamometer to know the force required to successfully detach the reattached fragment and by a microinfiltration test by using a 0.5% methylene blue solution followed by the optic microscope observation. Results. The compression test showed only a slight difference between the three groups, without any statistical significance. The infiltration test used to evaluate the marginal seal between the fracture fragment and the tooth demonstrated that etching with Er:YAG laser alone or in combination with orthophosphoric acid gives better results than orthophosphoric acid alone, with a highly significant statistical result. Discussion. Reattaching a tooth fragment represents a clinically proven methodology, in terms of achieving resistance to detachment, and the aim of this work was to demonstrate the advantages of Er:YAG laser on this procedure. Conclusion. This “in vitro” study confirms that Er:YAG laser can be employed in dental traumatology to restore frontal teeth after coronal fracture

Experimental Quantum Hamiltonian Learning

Efficiently characterising quantum systems, verifying operations of quantum devices and validating underpinning physical models, are central challenges for the development of quantum technologies and for our continued understanding of foundational physics. Machine-learning enhanced by quantum simulators has been proposed as a route to improve the computational cost of performing these studies. Here we interface two different quantum systems through a classical channel - a silicon-photonics quantum simulator and an electron spin in a diamond nitrogen-vacancy centre - and use the former to learn the latter's Hamiltonian via Bayesian inference. We learn the salient Hamiltonian parameter with an uncertainty of approximately $10^{-5}$. Furthermore, an observed saturation in the learning algorithm suggests deficiencies in the underlying Hamiltonian model, which we exploit to further improve the model itself. We go on to implement an interactive version of the protocol and experimentally show its ability to characterise the operation of the quantum photonic device. This work demonstrates powerful new quantum-enhanced techniques for investigating foundational physical models and characterising quantum technologies

NMR investigation of the Spontaneous Thermal- and/or Photoinduced Reduction of trans Dihydroxido Pt(IV) Derivatives.

The initial aim of the present work was the synthesis of the axial disuccinato Pt(IV) derivative of [PtCl2(cis-1,4-DACH)] (Kiteplatin, 1 in Figure 1) (DACH = diaminocyclohexane), which contains an isomeric form of the diamine ligand present in oxaliplatin (i.e., 1R,2R-DACH). The interest in this compound stems from its activity on several cisplatin and oxaliplatin-resistant cell lines. Oxidation of 1 with hydrogen peroxide affords cis,trans,cis- [PtCl2(OH)2(cis-1,4-DACH)] (2) which was treated with succinic anhydride in suitable solvents. To our surprise, in dimethylformamide (DMF) (50−70 °C or under light irradiation) or in dimethylsulfoxide (DMSO) (under light irradiation) the formation of the succinato complex cis,trans,cis-[PtCl2{OC(O)CH2CH2C(O)-OH}2(cis-1,4-DACH)] (3) was accompanied by reduction to 1. It was found that solvolysis of 2 and formation of a μ-oxo dinuclear species (5) is the key step. The dinuclear species can then undergo reduction to a 1:1 mixture of 1 and 2 with concomitant elimination of oxygen (1/2 O2 in the form of H2O2). The whole process is fostered by heat and/or light, which could favor solvolysis of 2 as well as decomposition of hydrogen peroxide to water and oxygen so preventing the reoxidation of 1 to 2. Because of its peculiar behavior, compound 5 could be exploited also for the development of a technology for water splitting