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The objective of this work is to design and characterize crystallizable silicate and borosilicate compositions for use in the production of smart, unconventional coatings on bioceramic implants. The concept behind this research is the development of a three-layer implantable system (joint prosthesis) comprising a ceramic substrate, a glass-derived trabecular coating and a glass-ceramic interlayer that joins the other two elements together. The outer porous coating should exhibit bone-like architecture, high mechanical strength and good bioactivity to bond to bone, whereas the interlayer should be chemically stable in biological fluids to avoid detachment between the joined parts. Glasses in the SiO 2 –Na 2 O–K 2 O–CaO–P 2 O 5 –B 2 O 3 –Al 2 O 3 system have been synthesized by a melting route and thermally treated to obtain glass-ceramic products. A selection of potentially suitable materials for the trabecular coating and interlayer was carried out on the basis of thermal properties and tendency to dissolve in simulated body fluids (SBF) so that the integrity of the final device might be maintained upon implantation. The glass selected for the trabecular coating was processed by sponge replica method to produce glass-ceramic scaffolds, in order to evaluate the material properties and performance in an embodiment plausibly close to the final application. The mechanical properties of the porous glass-ceramic, which mimicked the 3-D pore architecture of cancellous bone, were adequate for load-bearing applications such as joint prostheses. Formation of a surface apatite layer on scaffold struts upon soaking in SBF confirmed the excellent bioactivity of the material, which is a key precondition for in vivo osteointegration. [ABSTRACT FROM AUTHOR]

In this work we investigated the sintering behaviour of apatite-wollastonite (AW) glass-ceramic powders with the presence of alumina, firstly detected as a potentially useful surface contaminant derived from the ball milling of the powder, and then as a dopant in the glass formulation. All powders were benchmarked against AW without alumina. A small percentage of contamination (0.14 wt%) showed to delay the melting of material, and lower densification derived from a lower ability to crystallize and higher stability in the glassy states. The doped AW revealed that an increase in alumina favoured the formation of a glassy phase, increasing the degree of necking and the development of crystals. In conclusion, the introduction of alumina improves the AW glass-ceramic processability when content and process parameters are optimized. [ABSTRACT FROM AUTHOR]

Abstract A novel iron containing alkali alkaline earth borosilicate glass has been developed that can vitrify up to 30 wt% (dry weight) of a Magnox sludge waste in a homogeneous wasteform at a melting temperature of 1200 °C. Ce was used as a simulant of the actinide content in the waste. The waste was spiked with 0.5wt% of Cs 2 O of which 90% was retained in the glass. 60% of the Cl was also retained. Mg content limited the waste loading as loadings in excess of 30wt% led to the formation of forsterite and in some cases CeO 2 and MgFe 2 O 4 based spinels. PCT leach testing of the glasses for periods up to 180 days indicated the formation of an amorphous magnesium (alumino-)silicate hydrated layer on the glass surface together with barium rich crystalline precipitates. No Ce was detected in the leachate. [ABSTRACT FROM AUTHOR]

Based on the current UK decarbonization policy, a general outlook on potential routes for the glass industry to achieve net‐zero is discussed and the differentiation during decarbonization is specified. Biomass ash is considered a potential alternative raw material for low‐carbon glass manufacture as it is rich in certain advantageous components, chiefly network modifiers. Simple sieving processes were shown to effectively separate impurities such as S, Cl, and C from some biomass ashes according to particle size distribution. The concentration of undesirable impurities decreased with increasing particle size. Morphologies and X‐ray diffraction patterns of larger washed biomass ash particles indicated liquid/amorphous phase formation during biomass combustion. The washing of ashes was also shown to be a potential route to purification. A washed bracken ash relevant to both modern and ancient glass production was characterized for comparison. Ultraviolet‐visible near‐infrared (UV‐Vis‐near IR) absorption spectra of representative green container glasses produced using biomass ash confirmed that ∼5 wt.% ash in representative glass batches has little impact on the color and redox state of glasses; the redox status of glass produced using >2 mm biomass ash after washing was less reduced than that of glass produced using high levels (>∼9 wt.%) of >2 mm biomass ash after sieving alone, observed via the redox couple Cr3+/Cr6+ by UV‐Vis‐near IR absorption spectroscopy. [ABSTRACT FROM AUTHOR]

Three novel glass compositions, identified as NCL2 (SiO 2 -based), NCL4 (B 2 O 3 -based) and NCL7 (SiO 2 -based), along with apatite-wollastonite (AW) were processed to form sintered dense pellets, and subsequently evaluated for their in vitro bioactive potential, resulting physico-chemical properties and degradation rate. Microstructural analysis showed the carbonated hydroxyapatite (HCA) precipitate morphology following SBF testing to be composition-dependent. AW and the NCL7 formulation exhibited greater HCA precursor formation than the NCL2 and NCL4-derived pellets. Moreover, the NCL4 borate-based samples showed the highest biodegradation rate; with silicate-derived structures displaying the lowest weight loss after SBF immersion. The results of this study suggested that glass composition has significant influence on apatite-forming ability and also degradation rate, indicating the possibility to customise the properties of this class of materials towards the bone repair and regeneration process. [ABSTRACT FROM AUTHOR]

Eight novel silicate, phosphate and borate glass compositions (coded as NCLx, where x = 1 to 8), containing different oxides ( i.e. MgO, MnO 2 , Al 2 O 3 , CaF 2 , Fe 2 O 3 , ZnO, CuO, Cr 2 O 3 ) were designed and evaluated alongside apatite-wollastonite (used as comparison material), as potential biomaterials for bone tissue repair and regeneration. Glass frits of all the formulations were processed to have particle sizes under 53 μm, with their morphology and dimensions subsequently investigated by scanning electron microscopy (SEM). In order to establish the nature of the raw glass powders, X-ray diffraction (XRD) analysis was also performed. The sintering ability of the novel materials was determined by using hot stage microscopy (HSM). Ionic release potential was assessed by inductively coupled plasma optical emission spectroscopy (ICP-OES). Finally, the cytotoxic effect of the novel glass powders was evaluated for different glass concentrations via a colorimetric assay, on which basis three formulations are considered promising biomaterials. [ABSTRACT FROM AUTHOR]

For energy saving and CO2 emissions reduction, in addition to extending the range of suitable raw material sources for glass manufacture, compositional reformulation, and alternative raw materials have been studied in the context of industrial container and float‐type soda‐lime‐silica (SLS) glasses. Lithium, potassium, and boron were applied to modify benchmark glass compositions. Reformulation impacts on key glass properties including the viscosity‐temperature relationship, thermal expansion, liquidus temperature, forming behavior and color. Compared to the benchmark glass, representative of commercial SLS glasses, melting temperatures (taken as temperatures corresponding to log (viscosity/dPa·s) = 2) of reformulated glasses are reduced by 11°C‐55°C. Investigation of four industrial by‐products (seashell waste, eggshell waste, biomass ash, and rice husk ash), and their potential suitability as alternative glass batch raw materials, was also conducted. Seashell waste and biomass ash were successfully introduced into representative green glass formulations. [ABSTRACT FROM AUTHOR]

A novel apatite-wollastonite/poly(lactic acid) (AW/PLA) composite structure, which matches cortical and cancellous bone properties has been produced and evaluated in vitro and in vivo. The composites structure has been produced using an innovative combination of 3D printed polymer and ceramic macrostructures, thermally bonded to create a hybrid composite structure. In vitro cell assays demonstrated that the AW structure alone, PLA structure alone, and AW/PLA composite were all biocompatible, with the AW structure supporting the proliferation and osteogenic differentiation of rat bone marrow stromal cells. Within a rat calvarial defect model the AW material showed excellent osseointegration with the formation of new bone, and vascularisation of the porous AW structure, both when the AW was implanted alone and when it was part of the AW/PLA composite structure. However, the AW/PLA structure showed the largest amount of the newly formed bone in vivo, an effect which is considered to be a result of the presence of the osteoinductive AW structure stimulating bone growth in the larger pores of the adjacent PLA structure. The layered AW/PLA structure showed no signs of delamination in any of the in vitro or in vivo studies, a result which is attributed to good initial bonding between polymer and ceramic, slow resorption rates of the two materials, and excellent osseointegration. It is concluded that macro-scale composites offer an alternative route to the fabrication of bioactive bone implants which can provide a match to both cortical and cancellous bone properties over millimetre length scales. [ABSTRACT FROM AUTHOR]

Composites have clinical application for their ability to mimic the hierarchical structure of human tissues. In tissue engineering applications the use of degradable biopolymer matrices reinforced by bioactive ceramics is seen as a viable process to increase osteoconductivity and accelerate tissue regeneration, and technologies such as additive manufacturing provide the design freedom needed to create patient-specific implants with complex shapes and controlled porous structures. In this study a medical grade poly(l -lactide) (PLLA) was used as matrix while apatite-wollastonite (AW) was used as reinforcement (5 wt% loading). Premade rods of composite were pelletized and processed to create a filament with an average diameter of 1.6 mm, using a twin-screw extruder. The resultant filament was 3D printed into three types of porous woodpile samples: PLLA, PLLA reinforced with AW particles, and PLLA with short AW fibres. None of the samples degraded in phosphate buffered solution over a period of 8 weeks, and an average effective modulus of 0.8 GPa, 1 GPa and 1.5 GPa was obtained for the polymer, particle and fibre composites, respectively. Composite samples immersed in simulated body fluid exhibited bioactivity, producing a surface apatite layer. Furthermore, cell viability and differentiation were demonstrated for human mesenchymal stromal cells for all sample types, with mineralisation detected solely for biocomposites. It is concluded that both composites have potential for use in critical size bone defects, with the AW fibre composite showing greater levels of ion release, stimulating more rapid cell proliferation and greater levels of mineralisation. [ABSTRACT FROM AUTHOR]