Bioengineered tooth emulation systems for regenerative and pharmacological purposes

Genetic conditions, traumatic injuries, carious lesions and periodontal diseases are all responsible for dental pathologies. The current clinical approaches are based on the substitution of damaged dental tissues with inert materials, which, however, do not ensure full physiological recovery of the teeth. Different populations of dental mesenchymal stem cells have been isolated from dental tissues and several attempts have already been made at using these stem cells for the regeneration of human dental tissues. Despite encouraging progresses, dental regenerative therapies are very far from any clinical applications. This is tightly connected with the absence of proper platforms that would model and faithfully mimic human dental tissues in their complexity. Therefore, in the last decades, many efforts have been dedicated for the development of innovative systems capable of emulating human tooth physiology in vitro. This review focuses on the use of in vitro culture systems, such as bioreactors and "organ-on-a-chip" microfluidic devices, for the modelling of human dental tissues and their potential use for dental regeneration and drug testing

Ultra-precise measurement of optical frequency ratios

We developed a novel technique for frequency measurement and synthesis, based on the operation of a femtosecond comb generator as transfer oscillator. The technique can be used to measure frequency ratios of any optical signals throughout the visible and near-infrared part of the spectrum. Relative uncertainties of $10^{-18}$ for averaging times of 100 s are possible. Using a Nd:YAG laser in combination with a nonlinear crystal we measured the frequency ratio of the second harmonic $\nu_{SH}$ at 532 nm to the fundamental $\nu_0$ at 1064 nm, $\nu_{SH}/\nu_0 = 2.000 000 000 000 000 001 \times (1 \pm 7 \times 10^{-19})$.Comment: 4 pages, 4 figure

PRACTICAL REALIZATION OF THE DEFINITION OF THE METRE AT INRIM

In this paper we present the traceability chain for the calibration of the frequency of laser standards that realize the definition of the metre at the National Institute of Metrological Research (INRIM) in Italy in accordance with the mise en pratique issued by the CIPM. We describe the way our femtosecond laser frequency combs are referenced to the SI second and the new research activity on the production and testing of iodine cells

Bioengineered tooth emulation systems for regenerative and pharmacological purposes

Genetic conditions, traumatic injuries, carious lesions and periodontal diseases are all responsible for dental pathologies. The current clinical approaches are based on the substitution of damaged dental tissues with inert materials, which, however, do not ensure full physiological recovery of the teeth. Different populations of dental mesenchymal stem cells have been isolated from dental tissues and several attempts have already been made at using these stem cells for the regeneration of human dental tissues. Despite encouraging progresses, dental regenerative therapies are very far from any clinical applications. This is tightly connected with the absence of proper platforms that would model and faithfully mimic human dental tissues in their complexity. Therefore, in the last decades, many efforts have been dedicated for the development of innovative systems capable of emulating human tooth physiology in vitro. This review focuses on the use of in vitro culture systems, such as bioreactors and "organ-on-a-chip" microfluidic devices, for the modelling of human dental tissues and their potential use for dental regeneration and drug testing

Laser Frequency Stabilization for Aerospace Applications

Long term frequency stability of lasers is a key parameter in many research areas ranging from dimensional metrology to fundamental physics. Many solutions have been proposed by the scientific community and lasers whose frequency is referenced to molecular transitions are commonly used when long term stability and wavelength accuracy are needed. Our goal is the development of a frequency stabilization system with a relative frequency stability (Allan variance) of 1E-12 over 1 second integration time which will be suitable for aerospace applications. The frequency reference is a 10 cm long Fabry-Perot optical resonator which has been designed in order to withstand the huge launch loads (up to 30g at 1 kHz). As the stability of the resonant frequency is determined by the long term stability of the cavity length, a low CTE material (ULE) was adopted as the cavity spacer. During the laboratory tests the cavity has been housed inside a mechanical insulating vacuum chamber, thermally controlled by a digital system. The laser is referenced to one of the cavity resonances by means of a digital implementation of the Pound-Drever-Hall technique. An FPGA equipped with a small number of auxiliary components provides a flexible and reconfigurable digital system. A laser was locked to an iodine transition using the “digital PDH” and a classical analog system; the same frequency stability (parts in 1E13 over a 1 second integration time) was measured. Currently we are working on the implementation of the thermostat in order to properly length-stabilize the Fabry-Perot resonator and to characterize the coefficient of thermal expansion of the ULE spacer we are using