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International audience; Since the invention and further development of lasers in the 1960s, photonics has grown into a field that permeates virtually every aspect of modern life. As photonics deals with the generation, transmission, modulation, amplification, conversion, and detection of light, glasses have played crucial and central roles in a multitude of applications given glasses' diverse range of composi-tions, properties, and forms. They are also low-cost materials, recyclable and generally easy to fabricate. In homage to the United Nations International Year of Glass 2022, this paper reviews the past, present, and future of photonic glasses.

Barium fluorotellurite glasses doping with Ho3+, Yb3+, and Ho3+:Yb3 were fabricated using the conventional melt and quenching method, and their optical properties were studied using different optical spectroscopic techniques. The FITR absorption band at 3000 cm-1 was used to investigate OH- concentrations of the prepared glasses, which increased with Yb3+ content. However, it decreased by substituting a portion of BaF2 content with Ba2CO3 concentration. The electric dipole line strengths and Judd-Ofelt parameters were estimated using UV-visible-near infrared (NIR) optical absorption spectra to gain information on the rare earth ions doped glasses for laser applications. The various radiative parameters such as line strengths, optical intensity, and radiative rates from the higher energy levels, including 5F4 + 5S2, 5F5, 5I4, 5I5, 5I6 and 5I7, to the ground state, 5I8 have been reported and discussed. The influence of the Yb3+ and Ba2CO3 concentrations on the upconversion and downconversion photoluminescence emission intensities of the glasses prepared have been investigated by pumping with 450 nm and 976 nm excitation sources. Under 450 nm and 976 nm, the NIR photoluminescence emissions reveal a band ranging from 980 nm to 1220 nm attributing to an overlap between Yb3+ and Ho3+ transitions. The influence of Yb3+ concentration on photoluminescence lifetime at the 2F5/2 → 2F7/2, 5F4 + 5S2 →5I8 and 5I6 →5I8 transitions under 976 nm laser excitation has been studied and reported. The results indicate that lifetime decreases with increasing Yb3+ concentration attributing to an efficient energy transfer from Yb3+ to Ho3+ ions. The energy transfer efficiency from Yb3+ → Ho3+ has been examined, which rises from 30% to 47% upon increasing Yb3+ content. Nevertheless, it decreases with the mixing of BaF2 and Ba2CO3 lattice modifier contents. The results demonstrated that the 1200 nm (5I6 →5I8 transition) has remarkable potential for developing fiber lasers.

Ultrashort pulsed laser processing is well known for the precise removal of target tissue with less thermal effect which may be used as a non-invasive tool for tooth preparation in dentistry. However, optimizing the laser processing conditions beforehand is imperative to avoid excessive loss of tissue, preventing necrosis and nerve damage. The present work proposes a heat conduction model to simulate the femtosecond laser ablation profile and temperature field on the dental hard tissues (enamel and dentin). The model is developed based on the finite element simulation using COMSOL Multiphysics software. The present model is validated on enamel and dentin samples by comparing with the in vitro studies. The laser-tissue interaction is simulated for the dental hard tissues of 1.00 mm thickness using 2D heat conduction model. In order to compare the simulation results, a single scan laser irradiation experiments were carried out using 800 nm, 100 fs, Ti:Sapphire femtosecond laser at the scanning speed of 10 mm/s and repetition rate of 10 kHz. The surface morphology of the irradiated samples is measured by optical profiler and SEM images. The simulation and experimental results are compared and discussed. The proposed femtosecond laser ablation model can be used to understand the real-time ablation dynamics and also, to determine the temperature field as well as the ablation profile. The simulation can be handful tool for the clinician to optimise the laser processing conditions thus it will improve the precision of the laser surgery and reduce the nerve damage during tooth preparation.

Optical properties and energy transfer of fluorotellurite glasses doped with Sm3+ and Sm3+:Yb3+ in visible and near-infrared wavelength under three different excitation sources. E. Kumi-Barimah, Y. Chen, R. Tenwick, G. Sharma, A. Jha The School of Chemical and Process Engineering, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK Corresponding author e-mail: e.kumi-barimah@leeds.ac.uk Abstract: Here, we fabricated Sm3+ singly doped and Sm3+: Yb3+ codoped barium fluorotellurite-based glasses and examined their spectroscopic properties. New series of near-IR photoluminescence emissions of Sm3+ were observed under 405 and 450 excitation lasers. Fluorotellurite-based glasses have been investigated for numerous optical applications such as lasers, fibre optics, waveguides, and Raman gain devices. The fluorotellurite materials exhibit high linear and nonlinear refractive indices of ~2.0 and extended UV- and IR transparency (0.35 to 5.0mm). Above all, the glass host promotes the retention of large concentrations of RE3+-ions in an environment of depleted OH-ion, which is advantageous from the point of view of enhanced spectroscopic properties for light amplification in visible and near-IR. In this presentation, we have selected the Sm3+:Yb3+ codoped barium fluorotellurite glasses with the composition (in mol%): (80-x)TeO2-(10)ZnO-(10)BaF2-(1.0)Yb2O3–(x=0-1.0Sm2O3), which were synthesised by employing controlled atmosphere of melting in dry oxygen and quenching. The powder mixtures were melted in a gold crucible at 750 -800 oC in an oxygen atmosphere for 3 hrs using an electrical furnace. The molten glass was transferred into a pre-heated brass mould at 300 oC and then annealed at the same temperature for 3 hrs to remove stress. The glass was cut and polished for optical characterisation. We report on the UV-visible-NIR Raman spectroscopy, absorption spectra, Judd-Oflet parameters, and photoluminescence properties. The photoluminescence emission of Sm3+ and Sm3+-Yb3+ doped glasses prepared were collected by exciting with 405 nm, 450 nm, and 980 nm laser sources for comparison. The 405 nm and 450 nm excitations reveal new series of NIR photoluminescence emissions from Sm3+ ions, corresponding to 6F11/2state to6HJ(J=7/2, 9/2, 11/2) transitions. In addition, we analysed the dominant interaction and energy transfer processes such as non-resonant phonon-assisted, non-radiative process, and cross-relaxation between Sm3+-Sm3+ and Yb3+-Sm3+ ions upon exciting with a 976 nm laser. Figure 1: (a) Visible and (b) near-infrared (NIR) wavelengths photoluminescence spectra of 0.5 mol% Sm3+ doped barium fluorotellurite glass series under 450 nm excitation. References: E. Kumi-Barimah et al. Effect of Yb3+ on the Structural and Visible to Near-Infrared Wavelength Photoluminescence Properties in Sm3+-Yb3+-Codoped Barium Fluorotellurite Glasses. Materials, 15, 3314 (2022).

Over the last 25 years has seen an unprecedented increase in the growth of phonic components based on semiconductor lasers, glass and polymer based optical fibres, organic LED, and solid-state lasers. Each of these components suffers from its intrinsic materials related limitations, which then limit the performance in integrated devices. A solution to the materials limitation is to develop device fabrication strategy which then allows multi-materials processing on a substrate, without compromising the structural, thermal, and spectroscopic performances. The challenge then one confronts is that the semiconductors are grown on an MBE machine, whereas the polymeric thin film materials are fabricated by traditional spin coating. By comparison, the glass and crystal based materials are processed via sputtering, or sol-gel techniques. None of these techniques, therefore, are compatible for a single-step device fabrication, due to materials chemical and physical incompatibility. A vast majority of rare-earth ion doped glass- and crystal-based devices are often pumped with semiconductor lasers, which then suggests that the glass-semiconductor devices might perform better when structurally integrated, and that engineering such structures might lead to reduction in pump energy and high photon-to-photon conversion. In this presentation, we explain the nano- and femto-second pulsed laser deposition techniques for controlling the structure of thin-films grown on desired silica-on-Si (SiO2-Si), silica, and silicon substrates. Examples of materials deposition on dissimilar substrates for stress-matched waveguide fabrication are discussed and the light emission properties of rare-earth ion-doped glass, Si, polymer, and 2D-MoS2 films are explained. The thin film stress modelling tool (COMSOL) was used a priori for waveguide engineering for ascertaining the extent to which the structural incompatibility, so that the mismatch strain can be minimized during deposition by controlling thickness. The structure and spectroscopic properties of rare-earth ion doped thin films on silica, polymer, and semiconductor GaAs substrates were examined in detail and are reported. We demonstrate the formation of glass-polymer super lattice structures, ion-implanted waveguide structures, and nano-silicon deposited waveguides for semiconductor integration. The machining properties of such composite structures using femto-second Ti-sapphire lasers is also described, which clearly shows that such complex structures from start-to-finish can be fabricated using different types of pulsed lasers. The amplified spontaneous emission and gain properties of such waveguides are characterized for a range of device applications.

We report on the Sm

Purpose High clinical success rates have been reported with the Masquelet technique in the treatment of traumatic bone loss. An increasing number of studies suggest that various factors can influence the properties of induced membranes. Goal of this systematic review is to answer the following questions: (1) which are the ideal spacer properties (material, surface topography, antibiotic supplementation) to booster the quality and osteogenic potential of induced membranes? (2) what is the ideal time to perform the second-stage operation? Methods A systematic search using the keywords “((Masquelet) OR (Induced Periosteum)) AND ((Spacer) OR (Time))” was performed in PubMed, Embase and Cochrane Library according to PRISMA guidelines. Studies published up to the 23rd of February 2022 were included and assessed independently by two reviewers. Results Thirteen animal and 1 clinical studies were identified to address the above questions. Spacer materials used were PMMA, silicone, titanium, polypropylene, PVA, PCL and calcium sulfate. With the exception of PVA sponges, all solid materials could induce membranes. Low union rates have been reported with titanium and rough surfaced spacers. Scraping of the inner surface of the IM also increased bony union rates. In terms of the ideal timing to perform the second-stage evidence suggests that membranes older than 8 weeks continue to have regenerative capacities similar to younger ones. Conclusion Membranes induced by smooth PMMA spacers loaded with low concentrations of antibiotics showed powerful osteogenic properties. Other materials such as Polypropylene or Calcium sulfate can also be used with good results. Despite current recommendation to perform the second stage operation in 4–8 weeks, membranes older than 8 weeks seem to have similar regenerative capacities to younger ones.

In the FFC-Cambridge process, the cathodic dissociation of oxide and CO/CO2 production on carbon anode is the basis for metal production in a CaCl2 bath. Using an inert intermetallic anode, the CO2 evolution can be eliminated altogether with acceleration in the electro-reduction kinetics. In the presence of a carbon anode, the cathodic dissociation of TiO2 suffers from slow reduction kinetics of TiO2 to Ti metal, which can be enhanced significantly by the incorporation of alkali species in the TiO2 pellet at the cathode and in the CaCl2 bath in the presence of an intermetallic inert anode. With inert anode and incorporation of K+-ion in the TiO2 matrix and in the salt bath, nearly full metallization with greater than 99% of Ti metal containing 1500 ppm of oxygen was possible to achieve in less than 16 h of electro-reduction. The microstructural and chemical analysis of the metallic phase and its morphology revealed the presence of a layer of titanium metal that forms in the fast reduction reaction step in less than 5 h, after which the reaction rate slows down significantly before terminating in 16 h. The investigation showed that two different types of microstructures of metallic titanium were evident—a thin sheet-like material on the outer periphery of the reduced pellet and the dendritic core which was found to be under the peripheral sheet of the metallic layer. The mechanism of morphological and microstructural changes in the reduced form of titanium metal is explained.

Rare earth elements are helping drive the global transition towards a greener economy. However, the way in which they are produced is far from being considered green. One of the major obstacles to developing greener production methods and the design of novel processes and materials involving rare earth elements is the limited thermodynamic data available. In the present work, we apply a suite of methods to estimate the enthalpy of formation of several rare earth compounds, including a new method based on a linear relationship, established by the authors. Experimental values of the enthalpy of formation of LnCl3, LnOCl, LnPO4, Ln2O2S, Ln2O2CO3 and NaLnO2 were collated and used to assess the accuracy of the different methods, which were then used to predict values for compounds for which no data exists. It is shown that Mostafa et al.'s group contribution method and the linear relationship proposed by the authors give the lowest mean absolute error (

Bone healing is a complex process, and if not managed successfully, it can lead to non-union, metal-work failure, bacterial infections, physical and psychological patient impairment. Due to the growing urgency to minimise antibiotic dependency, alternative treatment strategies, including the use of nanoparticles, have attracted significant attention. In the present study, cerium oxide nanoparticles (Ce4+, Ce3+) have been selected due to their unique antibacterial redox capability. We found the processing routes affected the agglomeration tendency, particle size distribution, antibacterial potential, and ratio of Ce3+:Ce4+ valence states of the cerium oxide nanoparticles. The antibacterial efficacy of the nanoparticles in the concentration range of 50–200 µg/ml is demonstrated against Escherichia coli, Staphylococcus epidermis, and Pseudomonas aeruginosa by determining the half-maximal inhibitory concentration (IC50). Cerium oxide nanoparticles containing a more significant amount of Ce3+ ions, i.e., FRNP, exhibited 8.5 ± 1.2%, 10.5 ± 4.4%, and 13.8 ± 5.8% increased antibacterial efficacy compared with nanoparticles consisting mainly of Ce4+ ions, i.e., nanoparticles calcined at 815 °C.

A novel reduction reaction for extracting Cr2O3 from chromite ores is demonstrated by excluding the formation of carcinogenic chromate (Cr6+) intermediates. We have investigated in detail the underpinning high-temperature reduction reaction: FeCr2O4+Na2CO3+2[C]=[Fe]+Na2Cr2O4+3CO(g), which defines the process chemistry for the formation of sodium chromite (Na2CrO2) as an intermediate product for Cr2O3 extraction. After high-temperature reduction, the magnetic separation, aqueous and acid leaching of reaction products yielded 81 wt% and 70 wt% pure Cr2O3 from low (∼4 wt%) and high (>8 wt%) silica-containing chromite ores, respectively. The process diagram explains the extraction of Cr2O3, Fe-Cr alloy, Al2O3, and MgO-Al2O3-silicate, reuse of CO2 for Na2CO3 recovery, and energy generation from CO combustion for demonstrating Cr6+-free extraction of metallic and mineral values from chromite ores. The process chemistry demonstrates the extraction of 75-80 % pure Cr2O3 from NaCrO2 by leaching with 0.05-0.5 M dilute H2SO4 in controlled pH conditions. The detailed chemical analysis of leachates after Cr2O3 extraction shows that the acid leachates with residual concentrations of ∼150 ppm Cr3+-ions can be recycled in situ for reusing water, for eliminating the risk of Cr6+-ion formation from atmospheric oxidation. The novel extraction route may be able to displace the current oxidative process for chromite ore processing by retrofitting.

The calcium phosphate is the main mineral constituent of bone. Although there has been significant amount of research on finding ideal synthetic bone, no suitable scaffold material has yet been found. In this investigation, the iron doped brushite (CaHPO4·2H2O) has been investigated for osteogenic potential and mechanical properties. The synthesis of iron-oxide doping in the form of Fe2+,3+-ions were carried out using the solution based method in which the ammonium hydrogen phosphate and calcium nitrate solutions were used in stoichiometric ratio for synthesizing CaHPO4·2H2O, with doping concentrations of Fe2+,3+-ions between 5 mol% and 30 mol%. The synthesized powders were analysed using X-ray powder diffraction, FTIR, SEM and Raman spectroscopic techniques. The heat treatment of synthesized powder was carried out at 1000 °C in air for 5 h, and it was found that the dominant crystalline phase in samples with 2+,3+-ions enhances the phase fraction of FePO4 and amorphous phase. Amongst the Fe2+,3+-doped β-CPP minerals, it was found that the 10 mol% Fe2+,3+-doped β-CPP offers the best combination of bio-mechanical and osteogenic properties as a scaffold for bone tissue regenerative engineering.

Treatment of fractures remains challenging and carries a high economical burden to both patients and society. In order to prevent some of the complications, the use of bone adhesives has been proposed, but up to date, bone adhesives are not part of the current clinical practice. Early results of use of bone cements and bone glues are promising, focusing in the areas of highly fragmented fractures, fixation of long bone fractures, filling bone voids and defects, promoting osseointegration, preventing non-union while maintaining the reduction of fracture fixation. This review aims to describe the state-of-the-art of the development, properties and use of adhesives in fracture treatment.

The calcium phosphate is the main mineral constituent of bone. Although there has been significant amount of research on finding ideal synthetic bone, no suitable scaffold material has yet been found. In this investigation, the iron doped brushite (CaHPO

A novel reduction reaction for extracting Cr

Helicobacter pylori, a non-invasive gram-negative bacteria is well known for its direct cause and effect relationship with peptic ulcer, gastric or duodenal ulceration. Its severe effect on human begin with its colonization and production of various enzyme like Vacuolating cytotoxin, Urease and Heat shock proteins. Urease is complex spherical protein which causes hydrolysis of gastric urea to ammonia and CO 2 . The enzymatic reaction results in increase of gastric pH and hence results in gastric cancer. We present a photonic based technique to identify these proteins in its natural supernatant condition. The Raman spectrum of Helicobacter pylori is reported and the vibrational peaks are identified with corresponding chemical bonds in the biochemical enzyme. This can lay the foundation for future diagnostic tool for clinical detection of peptic ulcer, gastric or duodenal ulceration.

Jack bean urease is a complex biochemical enzyme with the unique monomeric structure of polypeptides with an active site containing 2 nickel ions. Its pH-based characterization is spectroscopically investigated in an acidic (Hydrochloric acid) environment for understanding its limit of detection.

Melting characteristics of high-density polyethylene (HDPE) mixed with nano-size ceramic fillers (hydroxyl apatite and yttria stabilised zirconia) was analysed using the isochronal heating rate between 10 °C min−1 and 80 °C min−1. In this investigation, the kinetics of melting of HDPE-ceramic composites was analysed using the Avrami equation and the Kissinger model, applied to the Avrami formalism. The magnitude of the apparent energy barrier for the melting of HDPE falls within a range of 12 kJ mol−1 and 22 kJ mol−1, with a tendency for heterogeneous melting which was determined by characterising the value of Avrami exponent, n found to vary between 1 and 2. The heterogeneous nature of melting was also confirmed using the scanning electron microscopy, from which the evidences for both nano- and micro-scale interactions of HDPE with ceramic fillers (HA and yttria stabilised zirconia) were confirmed on a microscopic scale. Keywords: Biocomposite, Nano filler, Melting kinetics, Crystallisation, DSC (differential scanning calorimetry)

Scaffolds and implants in orthopaedics and regenerative dentistry usually fail because of bacterial infections. A promising solution would be the development of biomaterials with both significant regenerative potential and enhanced antibacterial activity. Working towards this direction, fluorapatite was synthesised and doped with Sr2+ and Ce3+ ions in order to tailor its properties. After experiments with four common bacteria (i.e. E. Coli, S. Aureus, B. Subtilis, B. Cereus), it was found that the undoped and the Ce3+ doped fluorapatites present better antibacterial response than the Sr2+ doped material. The synthesised minerals were incorporated into chitosan scaffolds and tested with Dental Pulp Stem Cells (DPSCs) to check their regenerative potential. As was expected, the scaffolds containing Sr2+-doped fluorapatite, presented high osteoconductivity leading to the differentiation of the DPSCs into osteoblasts. Similar results were obtained for the Ce3+-doped material, since both the concentration of osteocalcin and the RUNX2 gene expression were considerably higher than that for the un-doped mineral. Overall, it was shown that doping with Ce3+ retains the good antibacterial profile of fluorapatite and enhances its regenerative potential, which makes it a promising option for dealing with conditions where healing of hard tissues is compromised by bacterial contamination.