Consolidation of porous carbonate stones by an innovative phosphate treatment: Mechanical strengthening and physical-microstructural compatibility in comparison with TEOS-based treatments

For preservation of stones used in Cultural Heritage, affected by weathering processes that threaten their cohesion and mechanical properties, the application of consolidants is a common practice. However, available consolidating products generally exhibit some drawbacks that hinder their performance, in terms of either mechanical efficacy, compatibility with the substrate and/or durability. Ethyl silicate is currently the most widely used among stone consolidants; nevertheless, its reduced efficacy on calcitic substrates, together with its temporary hydrophobicity, its tendency to crack and its common formulation with volatile organic solvent, make the research for alternative consolidants for carbonate stones necessary. In this paper, a recently proposed new consolidation treatment based on the formation of hydroxyapatite inside the stone was tested on two different porous carbonate stones (Globigerina Limestone and Giallo Terra di Siena), and compared with TEOS-based treatments, frequently used for the consolidation of these lithotypes. The results show that the hydroxyapatite treatment exhibits a good efficacy in terms of mechanical properties and, compared to TEOS, it causes less pronounced alterations in open porosity and water transport properties. This makes the new treatment a potentially valid alternative to TEOS, especially in those situations where the possible presence of water behind the consolidated layer (e.g. in case of rising damp, condensation or infiltration) might threaten the durability of the consolidation intervention

New Phosphate-Based Treatments for Carbonate Stone Consolidation and Protection

Carbonate stones on site undergo severe weathering processes, that make consolidation and protection necessary. However, currently available consolidants and protectives are far from being satisfactory when applied to this kind of materials. For this reason, in this thesis an innovative hydroxyapatite-based treatment was developed for limestone consolidation, marble consolidation and marble protection. Firstly, a new treatment protocol was set up for limestone and marble consolidation: solution precursor, concentration and pH, application method and possible additions were investigated to improve the treatment performance. Then, efficacy, compatibility and durability of the treatment were evaluated on these two lithotypes, in comparison with the products currently used for the same aim (ethyl silicate and ammonium oxalate). For marble, the treatment protocol developed in laboratory was also tested on a real historic artefact and on site. Moreover, a surface treatment for protecting marble against acidic rain was formulated, investigating how different parameters (starting solution pH and concentration, organic and inorganic additions) affect the morphology, composition and acid resistance of the treated surface. Excellent results were achieved: hydroxyapatite resulted an effective, compatible and durable consolidant for carbonate stone. Moreover, ethanol addition allowed to obtain a uniform, acid resistant protective hydroxyapatite layer on marble

Consolidation of sugaring marble by hydroxyapatite: some recent developments on producing and treating decayed samples

Consolidation of sugaring marble (i.e., marble affected by granular disaggregation) still lacks fully effective solutions. Consequently, the use of an innovative phosphate-based treatment, aimed at bonding calcite grains by formation of hydroxyapatite at grain boundaries, has recently been proposed. In this paper, firstly a novel method for producing artificially decayed marble samples, by contact with a heating plate, is proposed. Then, some results are presented about the effectiveness and the compatibility of two different formulations of the phosphate treatment, differing in terms of concentration of the phosphate precursor (3.0 M or 0.1 M aqueous solutions of diammonium hydrogen phosphate, DAP), possible ethanol addition to the DAP solution and number of DAP solution applications (1 or 2). The results of the study point out that the new weathering method allows to obtain specimens with a gradient in microstructural and mechanical properties with thickness, just like naturally weathered samples. Both phosphate treatments were able to significantly improve marble cohesion, without causing significant changes in thermal behaviour and aesthetic appearance after treatment. The addition of small quantities of ethanol to the DAP solution seems to be a very promising method for favouring HAP formation and improving the treatment performance

Foot Orthosis and Sensorized House Slipper by 3D Printing

In clinical practice, specific customization is needed to address foot pathology, which must be disease and patient-specific. To date, the traditional methods for manufacturing custom functional Foot Orthoses (FO) are based on plaster casting and manual manufacturing, hence orthotic therapy depends entirely on the skills and expertise of individual practitioners. This makes the procedures difficult to standardize and replicate, as well as expensive, time-consuming and material-wasting, as well as difficult to standardize and replicate. 3D printing offers new perspectives in the development of patient-specific orthoses, as it permits addressing all the limitations of currently available technologies, but has been so far scarcely explored for the podiatric field, so many aspects remain unmet, especially for what regards customization, which requires the definition of a protocol that entails all stages from patient scanning to manufacturing

FT-IR Spectral Signature of Sensitive and Multidrug-Resistant Osteosarcoma Cell-Derived Extracellular Nanovesicles

Osteosarcoma (OS) is the most common primary bone cancer in children and adolescents. Despite aggressive treatment regimens, the outcome is unsatisfactory, and multidrug resistance (MDR) is a pivotal process in OS treatment failure. OS-derived extracellular vesicles (EVs) promote drug resistance to chemotherapy and target therapy through different mechanisms. The aim of this study was to identify subpopulations of osteosarcoma-EVs by Fourier transform infrared spectroscopy (FT-IR) to define a specific spectral signature for sensitive and multidrug-resistant OS-derived EVs. EVs were isolated from sensitive and MDR OS cells as well as from mesenchymal stem cells by differential centrifugation and ultracentrifugation. EVs size, morphology and protein expression were characterized. FT-IR/ATR of EVs spectra were acquired in the region of 400-4000 cm(-1) (resolution 4 cm(-1), 128 scans). The FT-IR spectra obtained were consistently different in the EVs compared to cells from which they originate. A specific spectral signature, characterized by a shift and a new band (1601 cm(-1)), permitted to clearly distinguish EVs isolated by sensitive and multidrug-resistant OS cells. Our data suggest that FT-IR spectroscopy allows to characterize and define a specific spectral signature for sensitive and MDR OS-derived EVs

Consolidation of porous carbonate stones by an innovative phosphate treatment: mechanical strengthening and physical-microstructural compatibility in comparison with TEOS-based treatments

For preservation of stones used in Cultural Heritage, affected by weathering processes that threaten their cohesion and mechanical properties, the application of consolidants is a common practice. However, available consolidating products generally exhibit some drawbacks that hinder their performance, in terms of either mechanical efficacy, compatibility with the substrate and/or durability. Ethyl silicate is currently the most widely used among stone consolidants; nevertheless, its reduced efficacy on calcitic substrates, together with its temporary hydrophobicity, its tendency to crack and its common formulation with volatile organic solvent, make the research for alternative consolidants for carbonate stones necessary. In this paper, a recently proposed new consolidation treatment based on the formation of hydroxyapatite inside the stone was tested on two different porous carbonate stones (Globigerina Limestone and Giallo Terra di Siena), and compared with TEOS-based treatments, frequently used for the consolidation of these lithotypes. The results show that the hydroxyapatite treatment exhibits a good efficacy in terms of mechanical properties and, compared to TEOS, it causes less pronounced alterations in open porosity and water transport properties. This makes the new treatment a potentially valid alternative to TEOS, especially in those situations where the possible presence of water behind the consolidated layer (e.g. in case of rising damp, condensation or infiltration) might threaten the durability of the consolidation intervention

Black, Brown, and Powerful: Freedom Dreams in Unequal Cities

In April 2018, the Institute on Inequality and Democracy convened scholars, activists, policy advocates, community residents, and nonprofit workers to share and discuss research and action pertaining to processes of inequality in Los Angeles. We sought to shed light on the entangled structures of oppression, including urban displacement, housing precarity, racialized policing, criminal justice debt, forced labor, and the mass supervision and control of youth. Through keynote talks, group dialogue, and workshops, we analyzed how in Los Angeles, and elsewhere, black and brown communities face multiple forms of banishment and exploitation ranging from the criminalization of poverty to institutionalized theft.The question of racial banishment has been an important one for the Institute since its inauguration two years ago. This year though, amidst the troubled times of Trumpism, we wanted to shift our focus from banishment to freedom. In the reports that follow, you will find many examples of what Robin D.G. Kelley, a key presence at the Institute, has famously called “freedom dreams.” Located in, and thinking from South Central Los Angeles, the event’s participants provide insight into organizing frameworks and resistance strategies that challenge exclusion and refuse subordination. From tenant organizing to debtors’ unions, from underground scholars to educational reparations, visions of freedom abound. The Institute on Inequality and Democracy is convinced that university-based research can, and must, support such freedom dreams. Such partnership – between the public university and social justice movements – requires careful attention to the difficult task of decolonizing the university. This mandate is evident throughout this collection of reports. There is no easy alliance between academic power and banished communities; there is no obvious solidarity between urban plans and freedom dreams. This event was intended to be a step towards building such alliances, especially by reconstructing the curriculum and canon of knowledge

Bone on-a-chip: a 3D dendritic network in a screening platform for osteocyte-targeted drugs

Age-related musculoskeletal disorders, including osteoporosis, are frequent and associated with long lasting morbidity, in turn significantly impacting on healthcare system sustainability. There is therefore a compelling need to develop reliable preclinical models of disease and drug screening to validate novel drugs possibly on a personalized basis, without the need of in vivo assay. In the context of bone tissue, although the osteocyte (Oc) network is a well-recognized therapeutic target, current in vitro preclinical models are unable to mimic its physiologically relevant and highly complex structure. To this purpose, several features are needed, including an osteomimetic extracellular matrix, dynamic perfusion, and mechanical cues (e.g. shear stress) combined with a three-dimensional (3D) culture of Oc. Here we describe, for the first time, a high throughput microfluidic platform based on 96-miniaturized chips for large-scale preclinical evaluation to predict drug efficacy. We bioengineered a commercial microfluidic device that allows real-time visualization and equipped with multi-chips by the development and injection of a highly stiff bone-like 3D matrix, made of a blend of collagen-enriched natural hydrogels loaded with hydroxyapatite nanocrystals. The microchannel, filled with the ostemimetic matrix and Oc, is subjected to passive perfusion and shear stress. We used scanning electron microscopy for preliminary material characterization. Confocal microscopy and fluorescent microbeads were used after material injection into the microchannels to detect volume changes and the distribution of cell-sized objects within the hydrogel. The formation of a 3D dendritic network of Oc was monitored by measuring cell viability, evaluating phenotyping markers (connexin43, integrin alpha V/CD51, sclerostin), quantification of dendrites, and responsiveness to an anabolic drug. The platform is expected to accelerate the development of new drug aimed at modulating the survival and function of osteocytes

Customized biofilm device for antibiofilm and antibacterial screening of newly developed nanostructured silver and zinc coatings

Background Bacterial colonisation on implantable device surfaces is estimated to cause more than half of healthcare-associated infections. The application of inorganic coatings onto implantable devices limits/prevents microbial contaminations. However, reliable and high-throughput deposition technologies and experimental trials of metal coatings for biomedical applications are missing. Here, we propose the combination of the Ionized Jet Deposition (IJD) technology for metal-coating application, with the Calgary Biofilm Device (CBD) for high-throughput antibacterial and antibiofilm screening, to develop and screen novel metal-based coatings. Results The films are composed of nanosized spherical aggregates of metallic silver or zinc oxide with a homogeneous and highly rough surface topography. The antibacterial and antibiofilm activity of the coatings is related with the Gram staining, being Ag and Zn coatings more effective against gram-negative and gram-positive bacteria, respectively. The antibacterial/antibiofilm effect is proportional to the amount of metal deposited that influences the amount of metal ions released. The roughness also impacts the activity, mostly for Zn coatings. Antibiofilm properties are stronger on biofilms developing on the coating than on biofilms formed on uncoated substrates. This suggests a higher antibiofilm effect arising from the direct contact bacteria-coating than that associated with the metal ions release. Proof-of-concept of application to titanium alloys, representative of orthopaedic prostheses, confirmed the antibiofilm results, validating the approach. In addition, MTT tests show that the coatings are non-cytotoxic and ICP demonstrates that they have suitable release duration (> 7 days), suggesting the applicability of these new generation metal-based coatings for the functionalization of biomedical devices.Conclusions The combination of the Calgary Biofilm Device with the Ionized Jet Deposition technology proved to be an innovative and powerful tool that allows to monitor both the metal ions release and the surface topography of the films, which makes it suitable for the study of the antibacterial and antibiofilm activity of nanostructured materials. The results obtained with the CBD were validated with coatings on titanium alloys and extended by also considering the anti-adhesion properties and biocompatibility. In view of upcoming application in orthopaedics, these evaluations would be useful for the development of materials with pleiotropic antimicrobial mechanisms

Fabrication and characterization of biomimetic hydroxyapatite thin films for bone implants by direct ablation of a biogenic source

Biomimetic bone apatite coatings were realized for the first time by the novel Ionized Jet Deposition technique. Bone coatings were deposited on titanium alloy substrates by pulsed electron ablation of deproteinized bovine bone shafts in order to resemble bone apatite as closely as possible. The composition, morphology and mechanical properties of the coatings were characterized by GI-XRD, FT-IR, SEM-EDS, AFM, contact angle measurements, micro-scratch and screw-insertion tests. Different post-treatment annealing conditions (from 350 °C to 425 °C) were investigated. Bone apatite coatings exhibited a nanostructured surface morphology and a composition closely resembling that of the deposition target (i.e. natural bone apatite), also regarding the presence of magnesium and sodium ions. Crystallinity and composition of the coatings were strongly influenced by annealing temperature and duration; in particular, upon annealing at 400 °C and above, a crystallinity similar to that of bone was achieved. Finally, adhesion to the titanium substrate and hydrophilicity were significantly enhanced upon annealing, all characteristics being known to have a strong positive impact on promoting host cells attachment, proliferation and differentiation