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Yttrium stabilized zirconia (YSZ) ceramics doped with Eu3+ ions have been successfully fabricated by Spark Plasma Sintering (SPS) technique. The influence of the europium concentration and post-annealing process on the structural, optical, and luminescent properties of the ceramics has been studied. It is shown that an increase in the europium concentration from 0.1 to 3 wt% does not lead to significant changes in the transmission spectra. However, annealing in air atmosphere at temperature from 700 °C to 1300 °C significantly affects the transmission spectrum, as a possible consequenceofthe formation of oxygen vacancy defects. The analysis of the photoexcitation and photoluminescence spectra showed that the main excitation bands are determined by direct excitation of the 7F0 ground state of Eu3+ions to the higher 4f energy levels with further radiation transitionsfrom these states. Moreover, the europium ion in the obtained ceramics occupy low-symmetry sites without inversion center.The luminescence decay kineticsare described by a doubleexponential function with decay time τ1 ~ 20 ns and τ2~ 90 ns for intrinsic emission centers and millisecond (τ ~ 1.4 ms) for Eu3+emission, for all investigated ceramics. The luminescence spectra in nanosecond time region are characteristic for yttrium-stabilized zirconia and are caused by oxygen vacancies in the presence of heavy cations (Y3+ and Eu3+).

ContextMaturity-onset diabetes of the young (MODY) 8 is a rare form of monogenic diabetes characterized by a mutation in CEL (carboxyl ester lipase) gene, which leads to exocrine pancreas dysfunction, followed by β cell failure. Induced pluripotent stem cells can differentiate into functional β cells. Thus, β cells from MODY8 patients can be generated in vitro and used for disease modelling and cell replacement therapy.MethodsA genetic study was performed in a patient suspected of monogenic diabetes.ResultsA novel heterozygous pathogenic variant in CEL (c.1818delC) was identified in the proband, allowing diagnosis of MODY8. Three MODY8-iPSC (induced pluripotent stem cell) clones were reprogrammed from skin fibroblasts of the patient, and their pluripotency and genomic stability confirmed. All 3 MODY8-iPSC differentiated into β cells following developmental stages. MODY8-iPSC–derived β cells were able to secrete insulin upon glucose dynamic perifusion. The CEL gene was not expressed in iPSCs nor during any steps of endocrine differentiation.ConclusioniPSC lines from a MODY8 patient with a novel pathogenic variant in the CEL gene were generated; they are capable of differentiation into endocrine cells, and β cell function is preserved in mutated cells. These results set the basis for in vitro modelling of the disease and potentially for autologous β cell replacement.

The application of microfluidics for largescale rapid analytics holds great promise in the pharmaceutical diagnostics and analytical chemistry. Here we report a paper based microfluidic substrate designed by the impregnation of Silver nanoparticles. This study demonstrates the achievement of a thousand-fold increase in the successful detection level up to 10 ppb (90.8 nM) by employing Surface Enhanced Raman Spectroscopy (SERS) for the detection of Catechol. The presented sensor exhibits the following main features: (i) high specificity of enzyme (Hemocyanin)-based sensing, (ii) effective SERS sensitivity, (iii) easiness and cost-effectiveness of a paper-based platform. We rationalize these findings using the ab initio DFT simulations using Gaussian 09 whose theoretical calculations reflect the observed experimental Raman peaks.

NaYF4:Er,Yb upconversion luminescent nanoparticles (UCNPs) were prepared by hydrothermal methods at 180 °C for 24 h. The X-ray diffraction (XRD) and TEM (transmission electron microscopy) images show that the resulting 60 nm UCNPs possess a hexagonal structure. In this work, maleic anhydride (MA) was grafted on the surface of UCNPs to induce hydrophilic properties. The photoluminescence spectra (PL) show upconversion emissions centered around 545 nm and 660 nm under excitation at 980 nm. The luminescent inks, including UCNPs@MA, polyvinyl alcohol (PVA), deionized water (DI), and ethylene glycol (EG), exhibit suitable properties for screen printing, such as high stability, emission intensity, and tunable dynamic viscosity. The printed patterns with a height of 5 mm and a width of 1.5 mm were clearly observed under the irradiation of a 980 nm laser. Our strategy provides a new route for the controlled synthesis of hydrophilic UCNPs, and shows that the UCNPs@MAs have great potential in applications of anti-counterfeiting packing.

Looking for upconverting biocompatible nanoparticles, we have prepared by the sol–gel method, silica–calcia glass nanopowders doped with different concentration of Tm3+ and Yb3+ ions (Tm3+ from 0.15 mol% up to 0.5 mol% and Yb3+ from 1 mol% up to 4 mol%) and characterized their structure, morphology, and optical properties. X-ray diffraction patterns indicated an amorphous phase of the silica-based glass with partial crystallization of samples with a higher content of lanthanides ions. Transmission electron microscopy images showed that the average size of particles decreased with increasing lanthanides content. The upconversion (UC) emission spectra and fluorescence lifetimes were registered under near infrared excitation (980 nm) at room temperature to study the energy transfer between Yb3+ and Tm3+ at various active ions concentrations. Characteristic emission bands of Tm3+ ions in the range of 350 nm to 850 nm were observed. To understand the mechanism of Yb3+–Tm3+ UC energy transfer in the SiO2–CaO powders, the kinetics of luminescence decays were studied.

One of the current forefront in the field of photonic are flexible photonic research and development. The desired deliverable is to adjust the mechanical properties of materials to fabricate flexible photonic systems with various applications, e.g. gratings, channel waveguides, solar cells, protective coatings. It is well known that sol-gel metal oxide coatings may find applications as flexible coatings in photonics. Moreover, these materials can be easily functionalized to obtain materials with additional special, desired, properties like easy-to-clean, anti-fingerprint, anti-fogging and others, what is attractive for the potential of future commercialization of flexible photonic materials. In this work, we present the first step of research aimed to obtain silica-based coatings with appropriate adhesion on flexible substrates as poorly wettable surface - polymer PET and Ti-6Al-4V and 316L metallic thin foil as active oxide surface. The use of various types of substrates was aimed at presenting diversity in the possibilities of using the proposed coating materials. Nanoindentation, tensile test and scratch test of the investigated samples were studied. Measuring the mechanical properties of thin oxide films is difficult because it is usually impossible to detach of coating, not destroying its, from substrates. The thickness of coatings can range from a dozen to a few hundred nanometres, so complete methodology to determine a full set of mechanical properties is still lacking. In literature, the surface of samples is measured without a clear indication on coating properties, but on features which are the results of substrate-coating combinations.

In this work, the existence of different crystal field sites for the rare-earth-doped tin dioxide nanopowder and RE-doped SiO2-SnO2 glass-ceramics is investigated. The slightly different crystal field symmetries have been resolved by using site-selective fluorescence line-narrowing spectroscopy. The obtained results show that a variety of optically non equivalent sites exist for the europium ion in the tin dioxide oxide structure associated to different allowed positions of the oxygen vacancies, whereas additional spectral disorder is found in the case of the glass-ceramic matrix. Ultrafast spectroscopy performed on Eu3+-doped tin dioxide nanocrystals shows that host-rare earth energy transfer occurs at a transfer rate of about 1.5×106 s-1. Similar experiments carried out for the Er3+-doped glass-ceramic system also validate the hypothesis that both host and matrix-excited RE emissions are decoupled due to the different origins of the involved physical mechanisms.

The theoretical model of rare earth doped optical devices based on the rate equations and the power propagation equations can be employed for recovering, via an indirect approach, the rare earth spectroscopic parameters. As an example, the model for an erbium doped silica-tin dioxide, SiO2 - SnO2 : Er3+, glass ceramic waveguide is considered. Two different pumping schemes are employed to excite the erbium ions, the direct pumping at 378 nm and the indirect pumping at 307 nm via the tin dioxide. The achievable optical gain per unit length at 1533 nm is then evaluated for both pumping cases. The ratio between the two simulated optical gains is compared with the emission intensity measurements to estimate the value of the SnO2-Er3+ energy transfer coefficient. The particle swarm optimization algorithm is applied in order to find the SiO2 - SnO2 : Er3+ glass ceramic spectroscopic parameters which properly match the simulated optical gains ratio with the experimentally measured emission ratios. In the same way, the pump power coupled in the glass ceramic waveguide is also recovered. The SnO2-Er3+ energy transfer coefficient is estimated to be about 6.1 × 10-22 m3/s.

A variety of studies have been performed on WGM microresonators made of different materials and exploiting very high quality factors. This feature has allowed their use in a broad variety of applications including micro-lasers, optical filtering and switching, frequency conversion through non-linear effects, RF photonics and sensing. The easiest way to shape a glass spheroid with high quality factor is to use the surface tension during the thermal reflow of a highly transparent amorphous dielectric. Depending on the application, alternatives shapes like micro-bubbles or micro-bottles can be implemented in order to obtain specific performances. This manuscript reports the results we obtained on micro-laser sources in erbium doped microspheres, parametric frequency conversion in silica microspheres, stimulated Brillouin scattering in silica microbubbles, and non-linear effects in polymer coated or fluorophore filled glass microcavities.

Photoluminescent properties of nanocrystalline powders of the LiLa(PO 3 ) 4 system co-doped with Pr 3+ /Yb 3+ or Tm 3+ /Yb 3+ ions were reported. The powders were synthesized by precipitation method and annealed at 450 °C. Two series of the samples were prepared with 1 mol% of praseodymium or thulium ions and with various ytterbium content (from 2% up to 16%). Both the up- and downconversion energy transfers were studied, in particular, the spectra and kinetics of photoluminescence under blue (into Pr 3+ or Tm 3+ ions, respectively) and NIR (into Yb 3+ ions) excitations. The possible mechanisms of energy migration were discussed. Higher ytterbium concentration resulted in higher energy transfer efficiencies for both tetraphosphate systems.

Trabajo presentado en la 21st International Conference on Transparent Optical Networks (ICTON), celebrada en Angers (Francia), del 9 al 13 de julio de 2019, Since the pioneering work of Tick, Borrelli, Cornelius, and Newhouse on transparent glass ceramics performed in 1995, the research regarding photonic glass-ceramics is growing fast. From the considerable number of published studies, covering a broad spectrum of applications, it appears that reliable fabrication techniques and realization of effective photonic devices are the two crucial pivots for an important advance in this glass photonics area. The important results already obtained in rare earth-activated oxyfluoride, fluoride, and silicate transparent glass ceramics are well known. Regarding silicate-based photonic glass-ceramics the binary system SiO 2 -SnO 2 is really appealing when we look at the two above mentioned objectives.In this communication, a brief review of the state of art, consolidated results and recent advances in erbium doped SnO 2 -SiO 2 transparent glass-ceramics, obtained by sol-gel technology will be presented, and short-term perspectives will be outlined.

Low threshold coherent emission at 1.5 &micro, m is achieved using Er3+-doped dielectric 1D microcavities fabricated with a Radio Frequency-sputtering technique. The microcavities are composed of a half-wavelength Er3+-doped SiO2 active layer inserted between two Bragg reflectors consisting of ten, five, and seven pairs of SiO2/TiO2 layers, also doped with Er3+ ions. The morphology of the structure is inspected using scanning electron microscopy. Transmission measurements show the third and first order cavity resonance at 530 nm and 1.5 &micro, m, respectively. The photoluminescence measurements are obtained using the optical excitation at the third order cavity resonance using a 514.5 nm Ar+ laser or Xe excitation lamp at 514.5 nm, with an excitation angle of 30&deg, The full width at half maximum of the emission peak at 1535 nm decreased with the pump power until the spectral resolution of the detection system was 2.7 nm. Moreover, the emission intensity presents a non-linear behavior with the pump power and a threshold at about 4 &micro, W.

Cu2ZnSnS4 (CZTS) nanocrystals in oleylamine (OLA) and 1-dodecanethiol (1-DDT) solvents were successfully prepared via hot-injection method, to produce inks for the deposition of absorber layers in photovoltaic cells. In this process, 1-DDT acts as a coordinating ligand to control the nucleation and growth of CZTS nanocrystals, whereas lower amounts of OLA promote a homogeneous growth of the grains in the absorber layer. X-Ray Diffraction (XRD) revealed both tetragonal and hexagonal phases of CTZS in films obtained after soft thermal treatments (labeled TT0). In particular, 1-DDT is responsible for the formation of a greater percentage of the hexagonal phase (ZnS-wurtzite type) than that formed when only OLA is used. The thermal treatments have been varied from 500 &deg, C to 600 &deg, C for improving crystallization and eliminating secondary phases. Both features are known to promote CZTS thin films with band gap values typical of CZTS (1.5&ndash, 1.6 eV) and suitable resistivity. This study let to compare also the CZTS post-annealing without (TT1) and with sulfur vapor (TT2) in a tubular furnace. Only tetragonal CZTS phase is observed in the XRD pattern of CZTS thin films after TT2. A small presence of localized residues of secondary phases on the same samples was revealed by &mu, Raman measurements. The best values of band gap (1.50 eV) and resistivity (1.05 ohm.cm) were obtained after thermal treatment at 500 &deg, C, which is suitable for absorber layer in photovoltaic application.

In this work, we report on a structurally-colored composite colloidal crystal able to change its color in presence of different polar solvents such as butanol and to distinguish its isomers. Herein, polydimethylsiloxane (PDMS) infiltrated polystyrene opals are fabricated by means of a two steps approach and their final structure exhibits a green opalescence, the diffraction peak wavelength position changes as a function of the analytes spotted on the surface. In fact, the realized composites present a colorimetric variation in their response, since a remarkable red-shift of the diffraction peak is observed. An analytical model has been proposed and validated in order to assess the optical chromatic response, according to which the changing of the filling factor is the main element that produces the variation in the optical response. The selectivity, sensitivity and the reusability of the sensor have been investigated by monitoring the static reflectance spectra considering a mixture of 2-Methylpropan-2-ol (TerB) and water. Dynamic reflection spectra have been employed as an appropriate technique for the recognition of butanol isomers such as TerB, Butan-1-ol (NB) and Butan-2-ol (2B). The results demonstrate that the prepared photonic crystal sensing material and the interrogation approach used are a suitable tool for the development of low cost, portable sensors for homologues and isomers. © 2019 Elsevier B.V.

Barium gallo-germanate glasses co-doped with Ce3+ and Dy3+ were synthesized and their luminescence properties were studied using optical spectroscopy. The characteristic luminescence bands originating to electronic transitions of Ce3+ and Dy3+ ions were observed under direct excitation of Ce3+. Furthermore, the influence of rare earth ions concentration on luminescence properties of glass systems was examined. Luminescence lifetimes for the upper 4F9/2 excited state of Dy3+ ions were also evaluated and discussed in detail. The obtained experimental results indicate that energy transfer between these rare earth ions is possible. From the emission spectra, the Commission Internationale de I'Eclairage (CIE) chromaticity coordinates (x, y) are calculated in relation to potential application of germanate glass systems for white light emitting devices. It has been proved that our glass systems exhibit neutral/cool white emission originating from the simultaneous generation of several bands of Ce3+ and Dy3+ under the UV–visible light excitation.

International audience; We investigate the modal properties (effective index and modal gain) of an active, Erbium-doped single-mode slab waveguide made of silica tin-dioxide glass-ceramics on Silica. Completed with a photo-inscribed Bragg grating, such a structure is a good candidate for realizing an optically pumped laser emitter. For total Erbium concentration of 9.84 × 10−4 mol/cm3 and a cross-section (for stimulated transitions) of σ ≈ 2 × 10−25 m2 in a discussed structure, the maximum achievable material gain in DFB with Quarter-Wave phase Shift (QWS-DFB) is σ Ntot ≈ 23 m−1. Taking into account the confinement factor, the maximum achievable modal gain, in complex amplitude, over the length of 10 mm is at about (αmaxL) ≈ 0.09.

Objective To study pathogenic features of the somatic testicular microenvironment associated with idiopathic germ cell aplasia. Design Cross-sectional study. Setting Tertiary referral center for reproductive medicine. Patient(s) Testicular specimens from men with idiopathic nonobstructive azoospermia (iNOA) prospectively submitted to microdissection testicular sperm extraction. Of 20 specimens used for histology, 10 were also available for proteomic analysis. Primary Sertoli cells with normal karyotype and phenotype were also used. Intervention(s) Patients with iNOA were dichotomized according to a positive versus negative sperm retrieval at microdissection testicular sperm extraction, and on the isolated extracellular matrix (ECM) the proteomic analysis was performed. Main Outcome Measure(s) Proteomic analysis of the ECM from testicular specimens with positive versus negative sperm retrieval. Gene ontology enrichment was used to identify upstream regulators based on the 11 deregulated ECM proteins, which were validated by immunohistochemistry and quantitative polymerase chain reaction. Continuous variables were expressed as medians and interquartile range. Result(s) Germ cell aplasia was characterized by an increased signaling of the retinoic acid in Sertoli cells and associated with decreased expression of the basal membrane markers nidogen-2 and heparan sulfate proteoglycan-2. Decreased levels of the interstitial matrisome-associated factor IX and its regulator VKORC1 were, instead, coupled with decreased signaling of vitamin K in Leydig cells. An altered expression of a further eight ECM proteins was also found, including laminin-4 and laminin-5. Peripheral levels of the two vitamins were within the reference range in the two cohorts of iNOA men. Conclusion(s) We identified the pathogenetic signature of the somatic human testicular microenvironment, providing two vitamin-related mechanistic insights related to the molecular determinants of the idiopathic germ cell aplasia.

Silica microspheres were coated using an erbium activated silica hafnia thin film in order to produce microlasers. Lasing was observed and the lasing modes were identified. Only the modes whose electric field is located closest to the surface were found to exhibit lasing.

The paper illustrates both review and original simulation results obtained via the modelling of different set-ups based on optical microresonators for applications in optical sensing, lasing and spectroscopy. Passive microbubbles and microspheres coupled via long period fiber gratings (LPGs) and tapered fibers are designed and/or constructed for sensing of biological fluids in the near infrared (NIR) wavelength range. Rare earth doped chalcogenide glass integrated microdisks are designed for active sensing in the medium infrared (MIR) wavelength range. A home-made numerical code modelling the optical coupling and the active behavior via rate equations of ion population is employed for a realistic design, by taking into account the most important active phenomena in rare earths, such as the absorption rates, the stimulated emission rates, the amplified spontaneous emission, the lifetime and branching ratios, the ion-ion energy transfers and the excited state absorption. Optical coupling is obtained by employing ridge waveguides, for micro-disks, and tapered fibers, for microspheres and microbubbles. Different dopant rare earths as Erbium (Er3+) and Praseodymium (Pr3+) are considered.

In this paper, we described a versatile two steps approach for the realization of silica inverse opals functionalized with DNA-aptamers labelled with Cy3 fluorophore. The co-assembly method was successfully employed for the realization of high quality inverse silica opal, whilst the inverse network was functionalized via epoxy chemistry. Morphological and optical assessment revealed the presence of large ordered domains with a transmission band gap depth of 32%, after the functionalization procedure. Finite Difference Time-Domain (FDTD) simulations confirmed the high optical quality of the inverse opal realized. Photoluminescence measurements evidenced the effective immobilization of DNA-aptamer molecules labelled with Cy3 throughout the entire sample thickness. This assumption was verified by the inhibition of the fluorescence of Cy3 fluorophore tailoring the position of the photonic band gap of the inverse opal. The modification of the fluorescence could be justified by a variation in the density of states (DOS) calculated by the Plane Wave Expansion (PWE) method. Finally, the development of the aforementioned approach could be seen as proof of the concept experiment, suggesting that this type of system may act as a suitable platform for the realization of fluorescence-based bio-sensors.

The development of efficient luminescent systems, such as microcavities, solid-state lasers, integrated optical amplifiers, and optical sensors is the main topic in glass photonics. The building blocks of these systems are glass-ceramics activated by rare-earth ions because they exhibit specific morphologic, structural, and spectroscopic properties. Among various materials that could be used as nanocrystals to be imbedded in a silica matrix, tin dioxide presents some interesting peculiarities, e.g., the presence of tin dioxide nanocrystals allows an increase in both solubility and emission of rare-earth ions. Here, we focus our attention on Er3+&mdash, doped silica&mdash, tin dioxide photonic glass-ceramics fabricated by a sol-gel route. Although the SiO2-SnO2:Er3+ could be fabricated in different forms, such as thin films, monoliths, and planar waveguides, we herein limit ourselves to the monoliths. The effective role of tin dioxide as a luminescence sensitizer for Er3+ ions is confirmed by spectroscopic measurements and detailed fabrication protocols are discussed.

The development of efficient luminescent systems, such as microcavities, solid state lasers, integrated optical amplifiers, optical sensors is the main topic in glass photonics. The building blocks of these systems are glass-ceramics activated by rare earth ions because they exhibit specific morphologic, structural and spectroscopic properties. Among various materials that could be used as nanocrystals to be imbedded in silica matrix, tin dioxide presents some interesting peculiarities, e.g. the presence of tin dioxide nanocrystals allows increase in both solubility and emission of rare earth ions. Here, we focus our attention on Er3+ - doped silica – tin dioxide photonic glass-ceramics fabricated by sol-gel route. Although the SiO2-SnO2:Er3+ could be fabricated in different geometrical systems: thin films, monoliths and planar waveguides we herein limit ourselves to the monoliths. The effective role of tin dioxide as luminescence sensitizer for Er3+ ions is confirmed by spectroscopic measurements and detailed fabrication protocols are discussed.

The 1.5 – 2.1 μm luminescence germanate glass and double-clad optical fibers co-doped with Yb3+/Ho3+, Tm3+/Ho3+, Yb3+/Tm3+/Ho3+, and Er3+/Tm3+/Ho3+ have been analyzed. Fabricated germanium based glasses and optical fibers due to low phonon energy (805 cm−1) and high transparency up to 5.5 μm range enable to achieve broadband emission corresponding to radiative transitions of Er3+: 4I 13/2 → 4I 13/2 , Tm3+: 3F 4 → 3H 6 and Ho3+: 5I 7 →5I 8 . Maximum FWHM was obtained for following RE content: 563 nm – 0.7Er 2 O 3 /0.35Tm 2 O 3 /0.035Ho 2 O 3 (bulk glass), 265 nm – 0.7Tm 2 O 3 /0.15Ho 2 O 3 (bulk glass) and 337 nm – 0.7Yb 2 O 3 /0.15Ho 2 O 3 /0.4Tm 2 O 3 (double-clad optical fiber).

Rare earth doped materials play a very important role in the development of many photonic devices, such as optical amplifiers and lasers, frequency converters, solar concentrators, up to quantum information storage devices. Among the rare earth ions, ytterbium is certainly one of the most frequently investigated and employed. The absorption and emission properties of Yb3+ ions are related to transitions between the two energy levels 2F7/2 (ground state) and 2F5/2 (excited state), involving photon energies around 1.26 eV (980 nm). Therefore, Yb3+ cannot directly absorb UV or visible light, and it is often used in combination with other rare earth ions like Pr3+, Tm3+, and Tb3+, which act as energy transfer centres. Nevertheless, even in those co-doped materials, the absorption bandwidth can be limited, and the cross section is small. In this paper, we report a broadband and efficient energy transfer process between Ag dimers/multimers and Yb3+ ions, which results in a strong PL emission around 980 nm under UV light excitation. Silica-zirconia (70% SiO2-30% ZrO2) glass-ceramic films doped by 4 mol.% Yb3+ ions and an additional 5 mol.% of Na2O were prepared by sol-gel synthesis followed by a thermal annealing at 1000 &deg, C. Ag introduction was then obtained by ion-exchange in a molten salt bath and the samples were subsequently annealed in air at 430 &deg, C to induce the migration and aggregation of the metal. The structural, compositional, and optical properties were investigated, providing evidence for efficient broadband sensitization of the rare earth ions by energy transfer from Ag dimers/multimers, which could have important applications in different fields, such as PV solar cells and light-emitting near-infrared (NIR) devices.

Near-infrared emission in barium gallo-germanate glasses containing rare earth ions for broadband optical amplifiers were studied. Among the rare earths, the trivalent praseodymium and cerium ions were selected as an optically active dopants. In order to examine the spectroscopic properties of these glasses doped with Pr3+ and co-doped with Ce3+ and Pr3+ ions the luminescence spectra were registered. The energy transfer processes between cerium and praseodymium ions in barium gallo-germanate glasses have been also investigated. The intense near-infrared luminescence bands corresponding to characteristic transitions of Pr3+ ions in singly and doubly doped glass systems were observed. It has been proved that our glasses exhibit intense 1.5 μm emission originating from 1D2 → 1G4 transition of Pr3+ under direct excitation (445 nm). Moreover, the experimental results indicated that energy transfer between Ce3+ and Pr3+ is not effective for barium gallo-germanate glasses.

International audience; All Er3+ doped dielectric 1-D microcavity are fabricated by RF sputtering technique. The microcavity is composed of half wave Er3+ doped SiO2 active layer inserted, between two Bragg reflectors consisting of seven pairs of SiO2/TiO2 layers also doped with Er3+ ions. The morphology of the structure is inspected with scanning electron microscopy. Transmission measurements show the third and first order cavity resonance at 530 nm and 1535 nm, respectively. The photoluminescence measurements were obtained by optically exciting at the third order cavity resonance using 514.5 nm Ar+ laser with an excitation angle of 30°. The Full Width at Half Maximum of the emission peak at 1535 nm decrease with the pump power until the spectral resolution of the detection system of 2.3 nm. Moreover, the emission intensity presents a non-linear behavior with the pump power and a threshold at about 4 μW.

International audience; This work focuses on the fabrication processes and photonic assessment of SiO2-SnO2:Er3+ monoliths. To obtain the crack-free and densified system, the sol-gel derived synthesis protocols and heat-treatment processes were optimized. The absorption measurements were employed to assess the effect of the heat-treatment on the samples and specially to estimate the –OH content. The XRD patterns were used to investigate the crystallization as well as the structure of the monoliths. The emission spectra, performed at different excitation wavelengths, evidence the presence of Er3+ in the SnO2 nanocrystals and the energy transfer from SnO2 to the rare earth ions. In addition, the efficient role of SnO2 nanocrystals as Er3+ sensitizers are also experimentally confirmed in this system.

Optical microresonators are a very promising component for use in optoelectronics. They have very high quality factors and low mode volumes which makes them suitable for many applications such as lasing, sensing or non-linear optics. We will present our work on microspheres coated with sol-gel Er3+ activated 70SiO2 - 30HfO2. In particular the lasing properties of such microspheres will be presented. Different coating thicknesses will be employed and the peak lasing power will be discussed in respect to the coating thickness. The lasing peaks will be identified in respect to the radial and azimuthal numbers of the whispering gallery modes and the assignments will be discussed in terms of mode selectivity.

Microarray technology fails in detecting point mutations present in a small fraction of cells from heterogeneous tissue samples or in plasma in a background of wild-type cell-free circulating tumor DNA (ctDNA). The aim of this study is to overcome the lack of sensitivity and specificity of current microarray approaches introducing a rapid and sensitive microarray-based assay for the multiplex detection of minority mutations of oncogenes (KRAS, NRAS and BRAF) with relevant diagnostics implications in tissue biopsies and plasma samples in metastatic colorectal cancer patients. In our approach, either wild-type or mutated PCR fragments are hybridized in solution, in a temperature gradient, with a set of reporters with a 5' domain, complementary to the target sequences and a 3' domain complementary to a surface immobilized probe. Upon specific hybridization in solution, which occurs specifically thanks to the temperature gradients, wild-type and mutated samples are captured at specific location on the surface by hybridization of the 3' reporter domain with its complementary immobilized probe sequence. The most common mutations in KRAS, NRAS and BRAF genes were detected in less than 90 minutes in tissue biopsies and plasma samples of metastatic colorectal cancer patients. Moreover, the method was able to reveal mutant alleles representing less than 0,3% of total DNA. We demonstrated detection limits superior to those provided by many current technologies in the detection of RAS and BRAF gene superfamily mutations, a level of sensitivity compatible with the analysis of cell free circulating tumor DNA in liquid biopsy.

We report here the analysis of the light transmission properties of one dimensional photonic crystals made by multilayers of silicon dioxide and titanium dioxide. A precise fabrication by radiofrequency sputtering of a photonic crystal allows us to accurately model the transmission spectrum of the crystal, by taking into account the wavelength dependent refractive indexes of the materials. We found that, while the dispersion of silicon dioxide is in good agreement with data reported in literature, the dispersion of titanium dioxide is more critical. Using such dispersions we could fit the transmission spectra of silicon dioxide/titanium dioxide one dimensional photonic crystals made by spin coating layer deposition starting from nanoparticle colloidal dispersions. The fit takes into account the porosity of the layers and the losses due to Rayleigh scattering.

In this work, due to the challenge for improving the efficiency of photonic materials actived by Rare Earth ions (RE), Tin dioxide (SnO 2 ) nanocrystals based glass ceramic was employed and it was proved as a viable photonic material. The base material for doping RE ions was formed by embedding Tin dioxide nanocrystals into silica. The properties of the material were investigated by both simulations and experimental characterisation. The material was fabricated by sol-gel routes in different geometrical systems : thin films, monoliths and planar waveguides. The characterisation of the thin films showed the fundamental properties of the material : structural, morphological and optical properties. The presence of Tin dioxide nanocrystals led to the increase of both solubility and emission of RE ions. The energy transfer from the nanocrystals to the RE ions was proved by experiments and the result was again clarified by the simulations on the structure and the bandstructure of Er3+ ions substituting for Sn4+ ions in the nanocrystals. The results confirmed the advantages of Tin dioxide as luminescence sensitizer [1] for Er3+. Following the approaches of Tin dioxide based thin films, monoliths and planar waveguides have been fabricated for further processing into photonic devices : fibers, solid lasers and integrated circuits. In order to obtain the crack-free and densified monoliths, the synthesis and heat-treatment process of the xerogels have been optimized. Thermal analyses were performed in order to identify the heat-treatment stategy. Up to now, heat-treatment at 950°C for 100h has shown the best performance on H 2 O removal, densification of the monoliths and crystallization of SnO 2 nanocrystals. By characterisation of the exictation and emission of the monoliths, the indirect excitation due to energy transferring from SnO 2 into Er3+ has been shown to be more efficient than the other direct excitations. The monoliths excited at 335nm, which corresponds to the bandgap of SnO 2 nanocrystals, showed the highest emission intensity at 1534nm (Figure 1). The Tin dioxide based waveguides have shown the good transparency with transmittance higher than 90% in UV-Vis-NIR regions and waveguiding properties (Figure 2) with low losses.

Glass photonics are widespread, from everyday objects around us to high-tech specialized devices. Among different technologies, sol-gel synthesis allows for nanoscale materials engineering by exploiting its unique structures, such as transparent glass-ceramics, to tailor optical and electromagnetic properties and to boost photon-management yield. Here, we briefly discuss the state of the technology and show that the choice of the sol-gel as a synthesis method brings the advantage of process versatility regarding materials composition and ease of implementation. In this context, we present tin-dioxide-silica (SnO2-SiO2) glass-ceramic waveguides activated by europium ions (Eu3+). The focus is on the photorefractive properties of this system because its photoluminescence properties have already been discussed in the papers presented in the bibliography. The main findings include the high photosensitivity of sol-gel 25SnO(2):75SiO(2) glass-ceramic waveguides; the ultraviolet (UV)-induced refractive index change (Delta n similar to -1.6 x 10(-3)), the easy fabrication process, and the low propagation losses (0.5 +/- 0.2 dB/cm), that make this glass-ceramic an interesting photonic material for smart optical applications.

The paper describes the design of a medium infrared fiber laser based on a dysprosium-doped chalcogenide glass $\text{Dy}^{3+}: \text{Ga}_{5}\text{Ge}_{20}\text{Sb}_{10}\text{S}_{65}$ . To obtain a high efficiency, the fiber laser is followed by an optical amplifier. The optimized optical source exploits a master oscillator power amplifier (MOPA) configuration. The MOPA pump and signal wavelengths are 1709 and 4384 nm, respectively. Spectroscopic parameters measured on preliminary samples of chalcogenide glasses are taken into account to fulfill realistic simulations. The MOPA emission is maximized by applying a particle swarm optimization approach. For the dysprosium concentration ${\text{6}}\, \times\, {\text{10}}^{25}$ ions/ $\text{m}^{3}$ and the input pump power of 3 W, an output power of 637 mW can be obtained for optical fiber losses close to 1 dB $\text{m}^{-1}$ . The optimized MOPA configuration allows a laser efficiency larger than 21%. By considering the high beam quality provided by photonic crystal fibers, it is a good candidate for medium infrared light generation whose main applications include, but are not limited to, molecular spectroscopy and environmental monitoring.

In the paper we are investigating the interactions between the europium ions and the silver nanoparticles embedded in an antimony-germanate-silicate glass. Modification of Sb 2 O 3 - GeO 2 - SiO 2 - Al 2 O 3 - Na2O glass system by AgNO3 (up to 0.4 mol.%) allows us to obtain a visible effect of thermo-chemical reduction of Ag+ ions and characteristic absorption band localized at the wavelength of 450 nm. The effect of Ag concentration on structural and luminescent properties of fabricated glasses doped with 0.2 mol. % Eu 2 O 3 have been investigated. According to the luminescence analysis, in glass samples with Ag excited at 405 nm, the enhancement of 5D 0 → 7F 2 transition (616 nm) in Eu3+ ions has been observed just after the melting process. Based on these results, an effective embedding way of Ag particles in RE - doped optical fibers has been discussed.

Silica-tin dioxide thin films doped with Er3+ ions were fabricated and investigated. Different parameters such as heat-treatment temperatures, molar concentrations of SnO2 as well as Er3+ ions concentration were changed in order to obtain the best properties of presented thin films. Using several techniques, thin films were characterized and proved to be crack-free, water-free and smooth after a heat-treatment at 1200 °C. Aiming to application in optics, the transparency of thin films was also evidenced by transmission spectra. Based on the photoluminescence measurements, the mechanism of energy transfer from SnO2 nanocrystals to Er3+ ions was examined and discussed.

Sol-gel derived TiO2 thin films were prepared by spin- coating from an alcoholic solution of titanium isopropoxide. With the aim to develop titania layers suitable for memristive devices, the films were deposited onto test structures based on fused silica quartz substrates patterned with a Ti (5nm)/Pt (50nm) layer. The reported fabrication protocol is suitable for the development of a memristive device. Optical, structural, and morphological features of the samples were investigated with complementary techniques, such as scanning electron microscopy (SEM), prism coupling m-line and micro-Raman spectroscopy as well as transmittance and profilometry measurements. The quality of the surface of the obtained films was evaluated by SEM technique, and the morphology of samples deposited with different fabrication protocols was investigated. Additionally, a computer code for the refractive index and thickness estimation from the transmittance spectra was developed by unconstrained optimization procedure. The results of simulation were in good agreement with the experimental data obtained by m-line measurements. Moreover, the porosity of a specific set of test unannealed films has been estimated. TiO2 films exhibit thickness of tens of nm, and micro-Raman spectroscopy in conjunction with SEM indicate the presence of anatase phase after thermal annealing at 400 °C. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Pr3 +–Yb3 + co-doped transparent ZrF4-based bulk and planar waveguide glass ceramics (GCs) have been fabricated using the physical vapor deposition. X-ray diffraction and transmission electron microscopy analysis have shown the presence of a single crystalline phase that belongs to the LaF3–ZrF4 system. Upon 980 nm excitation, blue, orange and red emissions have been obtained both in bulk and waveguides. Intense luminescence of Yb3 + ions has been observed after excitation at 476 nm and is ascribed by to energy transfer (ET) from Pr3 + to Yb3 +. The ET efficiency was estimated to be 92% for 0.5 mol% Pr3 +–10 mol% Yb3 + co-doping.

The effect of increasing temperature on the optical, spectroscopic and structural properties of phospho-silicate nano-composites thin films SPNCTF and monolith SPNCM were studied. Doping the mentioned prepared forms of sample with some rare earth oxide such as Neodymium (Nd3+), Erbium (Er3+), Holmium (Ho3+) etc… SPNCRETF and SPNCREM have been prepared. Such materials could be promising for wave guide application, up-down shifting harvesting solar cell and could allow fabricating small devices with high gain in the telecommunication wavelength bands. The X-Ray diffraction XRD phases of the prepared samples deposited on appropriate substrates are analysed. The structural study revealed that the crystallite sizes of monolith and thin film phospho-silicate is in the nano-scale. The photo-luminescence properties have analyzed in the visible wavelength range as a function of sample composition. The optical properties will be studied by measuring the normal transmission and specular reflection, moreover the refractive index of the prepared samples will be calculated.

Pantothenate kinase‐associated neurodegeneration (PKAN) is an early onset and severely disabling neurodegenerative disease for which no therapy is available. PKAN is caused by mutations in PANK2 , which encodes for the mitochondrial enzyme pantothenate kinase 2. Its function is to catalyze the first limiting step of Coenzyme A (CoA) biosynthesis. We generated induced pluripotent stem cells from PKAN patients and showed that their derived neurons exhibited premature death, increased ROS production, mitochondrial dysfunctions—including impairment of mitochondrial iron‐dependent biosynthesis—and major membrane excitability defects. CoA supplementation prevented neuronal death and ROS formation by restoring mitochondrial and neuronal functionality. Our findings provide direct evidence that PANK2 malfunctioning is responsible for abnormal phenotypes in human neuronal cells and indicate CoA treatment as a possible therapeutic intervention.

The optical properties of novel antimony-germanate glass and optical fiber co-doped with Yb 3+ /Tm 3+ /Ho 3+ ions were presented. White light luminescence in glass was observed as a result of energy transfer with upconversion between donor (Yb 3+ ) and acceptors (Tm 3+ , Ho 3+ ) ions under 976 nm excitation. The double-clad optical fiber with off-set core co-doped with Yb 2 O 3 /Tm 2 O 3 /Ho 2 O 3 system was fabricated using a modified rod-in-tube technique. In glass co-doped with 0.5 mol%Yb 2 O 3 /0.1 mol%Tm 2 O 3 /0.2 mol%Ho 2 O 3 the spectral distribution of three luminescence bands (478, 545 and 660 nm) corresponds to x = 0.35 and y = 0.32 CIE coordinates. In comparison to glass the optical fiber emission are located in the green region (CIE, x = 0.37, y = 0.49).

BACKGROUND Low-level mutations in clinical tumor samples often reside below mutation detection limits, thus leading to false negatives that may impact clinical diagnosis and patient management. COLD-PCR (coamplification at lower denaturation temperature PCR) is a technology that magnifies unknown mutations during PCR, thus enabling downstream mutation detection. However, a practical difficulty in applying COLD-PCR has been the requirement for strict control of the denaturation temperature for a given sequence, to within ±0.3 °C. This requirement precludes simultaneous mutation enrichment in sequences of substantially different melting temperature (Tm) and limits the technique to a single sequence at a time. We present a temperature-tolerant (TT) approach (TT-COLD-PCR) that reduces this obstacle. METHODS We describe thermocycling programs featuring a gradual increase of the denaturation temperature during COLD-PCR. This approach enabled enrichment of mutations when the cycling achieves the appropriate critical denaturation temperature of each DNA amplicon that is being amplified. Validation was provided for KRAS (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) and TP53 (tumor protein p53) exons 6–9 by use of dilutions of mutated DNA, clinical cancer samples, and plasma-circulating DNA. RESULTS A single thermocycling program with a denaturation-temperature window of 2.5–3.0 °C enriches mutations in all DNA amplicons simultaneously, despite their different Tms. Mutation enrichments of 6–9-fold were obtained with TT-full-COLD-PCR. Higher mutation enrichments were obtained for the other 2 forms of COLD-PCR, fast-COLD-PCR, and ice-COLD-PCR. CONCLUSIONS Low-level mutations in diverse amplicons with different Tms can be mutation enriched via TT-COLD-PCR provided that their Tms fall within the denaturation-temperature window applied during amplification. This approach enables simultaneous enrichment of mutations in several amplicons and increases significantly the versatility of COLD-PCR.

Er3+ doped niobic-tungsten-tellurite glasses doped with concentration of Er3+ ion up to 3 wt% were fabricated. The effect of Er3+ doping concentration on thermal stability and optical properties was investigated in order to obtain the most suitable rare earth content for developing 1.5 micron compact fiber amplifier pumped with a commercial telecom 980 nm laser diode. The maximum doping concentration allowed was found to be around 1.77 x 10^20 ions/cm^3, for which a broad 1.5 micron emission spectra of 65 nm FWHM and a lifetime of 3.4 ms for the 4I13/2 level was measured

The efficiency of semiconductor solar cells may be improved by inserting in the front or rear of the solar cell an optically active layer doped with rare earth ions which acts as "down-converter" (DC) or" up-converter "(UC). This is just one of the possibilities that involve several structures and geometries such as waveguide configuration and radiation trapping systems. Among these systems glass ceramics play a crucial role especially because they combine the optical properties of glasses with the spectroscopic properties of the crystals activated by luminescent species. In this work we will give a short review regarding the research already performed by the team in the field of down-conversion process. We will focus the attemption on the cooperative energy transfer between donor and acceptor ions taking as example the interaction among one Tb3+ ion and two Yb3+ ions allowing to cut one high energy photon at wavelength shorter than 488 nm into two low energy photons around 980 nm. The choice of the matrix is another crucial point to obtain an efficient down conversion processes with rare earth ions; we demonstrated that the Tb3+/Yb3+ energy transfer efficiency in a 70SiO2-30HfO2 glass-ceramic waveguide is effective.

Nanocrystalline diamond (NCD) thin films are ideal to realize platform for bio-chemical sensors. They interface in a very specific way with the environment and the surface termination controls their electrochemical behavior. Generally the as-deposited NCD diamond surface is hydrogen terminated and several techniques are reported to obtain covalent bonding of biological matter. Among others, amino-functional groups are very versatile linkers to biomolecules. Grafting of amino groups to the diamond surface includes: chlorination and exposure to ammonia gas under thermal conditions, radio-frequency plasma or a one step method consisting of UV irradiation in a pure ammonia atmosphere. This last technique is very promising, combining surface functionalization with the realization of SGFETs (Solution Gate FET), and thus being compatible with semiconductor technologies. Experimental data from literature show that ammonia functional groups are always accompanied by the presence of oxygen which degrades the NCD conductivity. In this work we report on XPS in situ study to understand the role of oxygen in the one step amination process. Five NCD samples with different surface terminations (hydrogenated, plasma oxidized, chemically oxidized and UV oxidized) were irradiated with UV photons in different atmospheres (pure NH3 or NH3 + O2). XPS analysis shows that the presence of oxygen, both on the surface and in the gas mixture, strongly increases the efficiency of the UV surface amination.