scholarly journals Vibrational disorder and densification-induced homogenization of local elasticity in silicate glasses

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Omar Benzine ◽  
Zhiwen Pan ◽  
Courtney Calahoo ◽  
Michal Bockowski ◽  
Morten M. Smedskjaer ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Silicate Glass ◽  
Spectroscopic Data ◽  
Glass Structure ◽  
Soda Lime ◽  
Magic Angle Spinning ◽  
Homogeneous Distribution ◽  
Magic Angle ◽  
Log Normal ◽  
Permanent Densification

AbstractWe report the effect of structural compaction on the statistics of elastic disorder in a silicate glass, using heterogeneous elasticity theory with the coherent potential approximation (HET-CPA) and a log-normal distribution of the spatial fluctuations of the shear modulus. The object of our study, a soda lime magnesia silicate glass, is compacted by hot-compression up to 2 GPa (corresponding to a permanent densification of ~ 5%). Using THz vibrational spectroscopic data and bulk mechanical properties as inputs, HET-CPA evaluates the degree of disorder in terms of the length-scale of elastic fluctuations and the non-affine part of the shear modulus. Permanent densification decreases the extent of non-affine elasticity, resulting in a more homogeneous distribution of strain energy, while also decreasing the correlation length of elastic heterogeneity. Complementary 29Si magic angle spinning NMR spectroscopic data provide a short-range rationale for the effect of compression on glass structure in terms of a narrowing of the Si–O–Si bond-angle and the Si–Si distance.

scholarly journals Development of Robust Chitosan–Silica Class II Hybrid Coatings with Antimicrobial Properties for Titanium Implants

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 534 ◽  
Author(s):  
Zach Gouveia ◽  
Hiran Perinpanayagam ◽  
Jesse Zhu
Keyword(s):  
Antimicrobial Properties ◽  
Class Ii ◽  
Magic Angle Spinning ◽  
Titanium Implants ◽  
Hybrid Coatings ◽  
Homogeneous Distribution ◽  
Magic Angle ◽  
Coating Materials ◽  
Angle Spinning ◽  
Tensile Adhesion

The purpose of this study was to develop robust class II organic–inorganic films as antibacterial coatings on titanium alloy (Ti6Al4V) implants. Coating materials were prepared from organic chitosan (20–80 wt.%) coupled by 3-glycydoxytrimethoxysilane (GPTMS) with inorganic tetraethoxysilane (TEOS). These hybrid networks were imbedded with antimicrobial silver nanoparticles (AgNPs) and coated onto polished and acid-etched Ti6Al4V substrates. Magic-angle spinning nuclear magnetic resonance (13CMAS-NMR), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and the ninhydrin assay, confirmed the presence and degree of covalent crosslinking (91%) between chitosan and GPTMS. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) identified surface roughness and microtopography on thin films and confirmed homogeneous distribution of elements throughout the coating. Cross-hatch and tensile adhesion testing demonstrated the robustness and adherence (15–20 MPa) of hybrid coatings to acid-etched titanium substrates. Staphylococcus aureus and Escherichia coli cultures and their biofilm formation were inhibited by all hybrid coatings. Antibacterial effects increased markedly for coatings loaded with AgNPs and appeared to increase with chitosan content in biofilm assays. These results are promising in the development of class II hybrid materials as robust and highly adherent antibacterial films on Ti6Al4V implants.

Investigation of the Properties of Soda-Lime Silicate Glass Doped with TiO2

2014 ◽  
Vol 979 ◽  
pp. 128-131 ◽  
Author(s):  
E. Meechoowas ◽  
Usanee Pantulap ◽  
T. Jitwatcharakomal
Keyword(s):  
Silicate Glass ◽  
Glass Structure ◽  
Glass Ceramics ◽  
Soda Lime ◽  
Color Measurement ◽  
Glass Cullet ◽  
Calculated Activation Energy ◽  
Lower Thermal Expansion ◽  
Soda Lime Silicate Glass ◽  
Calculated Activation

In this study, the properties of re-melted soda-lime silicate glass cullet doped with TiO2 were investigated in order to study the potentials to use as parent glass for glass-ceramics. TiO2 of 0.5, 1 and 3 mol% was doped into the 71SiO2-10Na2O-6K2O-5CaO-4MgO-2SrO-TiO2-Al2O3 glass cullet and melted at 1500°C for 3 hours, and then annealed at 550 °C. The optical and physical properties were examined. It was found that the refractive index and density of glasses were raised with increasing of TiO2 concentration. The optical properties measured by UV-Vis spectrophotometer showed that the UV edge in the absorption spectra was shifted to a higher wavelength, and the transmission at 583 nm was decreased. The CIE L*a*b* color measurement showed that the glasses were slightly colorless but the appearance of yellow increased with higher TiO2 concentration. Lower thermal expansion coefficient and higher glass transition temperature as well as the dilatometric softening point were observed as the concentration of TiO2 was increasing. Finally, the calculated activation energy was 476, 493, 506 and 637 kJ/mol with 0, 0.5, 1 and 3 mol% doped TiO2, respectively. At doped TiO2 of 3 mol%, the properties of glass were changed rapidly due to the substitution of [Ti4+] in local [Si4+] resulting in increasing the bond strength in glass structure.

Probing the Structure and Crystallinity of a Lithium Silicate Glass by29Si Magic-Angle-Spinning NMR Spectroscopy

1985 ◽  
Vol 24 (1) ◽  
pp. 61-62 ◽  
Author(s):  
C. N. R. Rao ◽  
John M. Thomas ◽  
Jacek Klinowski ◽  
U. Selvaraj ◽  
K. J. Rao ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Silicate Glass ◽  
Magic Angle Spinning ◽  
Lithium Silicate ◽  
Magic Angle ◽  
Angle Spinning ◽  
Lithium Silicate Glass

scholarly journals Design & development of a novel glass polyalkenoate cement for sternal fixation and repair, in the event of median sternotomy surgery

2021 ◽  
Author(s):  
Adel M.F. Alhalawani
Keyword(s):  
Glass Structure ◽  
Open Heart Surgery ◽  
Median Sternotomy ◽  
Magic Angle Spinning ◽  
Size Analysis ◽  
Wound Complications ◽  
Magic Angle ◽  
X Ray ◽  
Sternal Closure ◽  
Mole Percentage

Median sternotomy surgery is the gold standard for cardiac/thoracic procedures such as open-heart surgery. With over one million median sternotomy surgeries performed worldwide every year, sternal wound complications pose a serious risk to the health of affected patients. Various techniques have been used for sternal fixation including wiring, plate-screw systems and cementing. The ideal sternal closure device is the one which has mechanical properties suited to the local environment, biocompatibility, radio-opacity, cost-effectiveness and ease of removal when necessary. None of the techniques that have been utilized for sternal fixation to date address all of these requirements. Glass polyalkenoate cements (GPCs) have a long history of use in restorative and orthodontic dentistry and ear, nose and throat (ENT) surgery but have yet to be indicated for musculoskeletal applications. This dissertation relates to the development of new GPC-based adhesives for use in sternal closure. A series of novel glasses based on the system 48SiO2-(36-X) ZnO-6CaO-8SrO-2P2O5-XTa2O5 with X varying from 0.0 to 8.0 mole percentage were fabricated and characterized. The structural features as a function of Ta2O5 content were investigated by network connectivity (NC) calculations, x-ray diffraction (XRD), particle size analysis (PSA), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and magic angle spinning-nuclear magnetic resonance (MAS-NMR). The thermal properties of the glasses were obtained by performing simultaneous thermal analysis (STA). The effect of glass structure on pH and solubility was also evaluated. The formulated glasses were used to prepare GPC adhesive materials and tested for their suitability for sternal fixation. The data collected has confirmed that substituting up to 0.5 mole percentage of ZnO with Ta2O5 in the glass system under study resulted in the formation of adhesives that are deemed suitable for sternal fixation. The formulated cements, based on the use of glasses containing no greater than 0.5 mole percentage of Ta2O5 have rheology, strength, radiopacity, antibacterial and in-vitro behavior suitable for sternal fixation. To the best knowledge of the candidate, this dissertation is the first to report the use of tantalum-containing GPC-based adhesives for sternal closure. Based on the obtained results, the formulated adhesives can be used in conjunction with sternal cable ties (current standard method) to offer optimal fixation for patients and reduce post-operative complications such as bacterial infection and pain from micro-motion.

scholarly journals Design & development of a novel glass polyalkenoate cement for sternal fixation and repair, in the event of median sternotomy surgery

2021 ◽  
Author(s):  
Adel M.F. Alhalawani
Keyword(s):  
Glass Structure ◽  
Open Heart Surgery ◽  
Median Sternotomy ◽  
Magic Angle Spinning ◽  
Size Analysis ◽  
Wound Complications ◽  
Magic Angle ◽  
X Ray ◽  
Sternal Closure ◽  
Mole Percentage

Median sternotomy surgery is the gold standard for cardiac/thoracic procedures such as open-heart surgery. With over one million median sternotomy surgeries performed worldwide every year, sternal wound complications pose a serious risk to the health of affected patients. Various techniques have been used for sternal fixation including wiring, plate-screw systems and cementing. The ideal sternal closure device is the one which has mechanical properties suited to the local environment, biocompatibility, radio-opacity, cost-effectiveness and ease of removal when necessary. None of the techniques that have been utilized for sternal fixation to date address all of these requirements. Glass polyalkenoate cements (GPCs) have a long history of use in restorative and orthodontic dentistry and ear, nose and throat (ENT) surgery but have yet to be indicated for musculoskeletal applications. This dissertation relates to the development of new GPC-based adhesives for use in sternal closure. A series of novel glasses based on the system 48SiO2-(36-X) ZnO-6CaO-8SrO-2P2O5-XTa2O5 with X varying from 0.0 to 8.0 mole percentage were fabricated and characterized. The structural features as a function of Ta2O5 content were investigated by network connectivity (NC) calculations, x-ray diffraction (XRD), particle size analysis (PSA), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and magic angle spinning-nuclear magnetic resonance (MAS-NMR). The thermal properties of the glasses were obtained by performing simultaneous thermal analysis (STA). The effect of glass structure on pH and solubility was also evaluated. The formulated glasses were used to prepare GPC adhesive materials and tested for their suitability for sternal fixation. The data collected has confirmed that substituting up to 0.5 mole percentage of ZnO with Ta2O5 in the glass system under study resulted in the formation of adhesives that are deemed suitable for sternal fixation. The formulated cements, based on the use of glasses containing no greater than 0.5 mole percentage of Ta2O5 have rheology, strength, radiopacity, antibacterial and in-vitro behavior suitable for sternal fixation. To the best knowledge of the candidate, this dissertation is the first to report the use of tantalum-containing GPC-based adhesives for sternal closure. Based on the obtained results, the formulated adhesives can be used in conjunction with sternal cable ties (current standard method) to offer optimal fixation for patients and reduce post-operative complications such as bacterial infection and pain from micro-motion.

scholarly journals Solid State NMR: A Powerful Tool for the Characterization of Borophosphate Glasses

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 428 ◽  
Author(s):  
Grégory Tricot ◽  
Lazzat Alpysbay ◽  
Bertrand Doumert
Keyword(s):  
Solid State ◽  
Quantum Coherence ◽  
Glass Structure ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Local Order ◽  
Magic Angle ◽  
Multiple Quantum ◽  
Borophosphate Glasses ◽  
Heteronuclear Multiple Quantum Coherence

This review will show how solid state nuclear magnetic resonance (NMR) has contributed to a better understanding of the borophosphate glass structure. Over the last fifteen years, 1D and 2D magic angle spinning (MAS)-NMR has been used to produce key information about both local and medium range organization in this type of glass. After a brief presentation on borophosphate glasses, the paper will focus on the description of the local order of phosphate and borate species obtained by 1D 31P-and 11B-MAS-NMR experiments, with a special emphasis on the improvements obtained at high magnetic fields on the borate speciation description. The last part of this review will show how correlation NMR provided new insights into the intermediate length scale order. Special attention will be paid to the quantitative data retrieved from 11B/31P REDOR-based NMR sequences and to the qualitative connectivity schemes observed on the 2D 11B/31P maps edited with the heteronuclear multiple quantum coherence (HMQC) NMR techniques.

Investigation of Lead Borosilicate Glass Structure With 207Pb and 11B Solid-State NMR

2000 ◽  
Vol 658 ◽  
Author(s):  
James M. Gibson ◽  
Frederick G. Vogt ◽  
Amy S. Barnes ◽  
Karl T. Mueller
Keyword(s):  
Solid State ◽  
Structural Information ◽  
Structural Parameters ◽  
Glass Structure ◽  
Active Role ◽  
Magic Angle Spinning ◽  
Lead Content ◽  
Magic Angle ◽  
Multiple Quantum ◽  
Borosilicate Glasses

ABSTRACTA series of three lead borosilicate glasses were synthesized and analyzed for structural information with both 11B and 207Pb solid-state nuclear magnetic resonance (NMR) spectroscopic methods. Results showed that increasing lead content caused lead to take a more active role in the network as a former and that the populations in these sites can be approximately quantified. 207Pb phase-adjusted-spinning sidebands (PASS), 11B magic-angle spinning (MAS), and 11B multiple-quantum MAS (MQMAS) experiments were used to determine structural parameters for the two nuclei. The 207Pb PASS experiment showed that at higher lead content, more covalent bonding was present. This principle was demonstrated in both an overall shift of the spectral resonances and a quantitative change in site ratios. The 11B MAS experiment showed that the ratio of BO3 to BO4 units was dependent on the amount of lead and boron, consistent with previous studies. Preliminary 11B MQMAS experiments failed to detect any BO3– units, previously hypothesized to exist in this system.

Pulse Shaped Dynamic Nuclear Polarization Under Magic Angle Spinning

2019 ◽  
Author(s):  
ASIF EQUBAL ◽  
Kan Tagami ◽  
Songi Han
Keyword(s):  
Electron Spin ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Total Electron ◽  
Spin Lattice ◽  
Maximum Benefit ◽  
Selective Saturation ◽  
Angle Spinning

In this paper, we report on an entirely novel way of improving the MAS-DNP efficiency by shaped μw pulse train irradiation for fast and broad-banded (FAB) saturation of the electron spin resonance. FAB-DNP achieved with Arbitrary Wave Generated shaped μw pulse trains facilitates effective and selective saturation of a defined fraction of the total electron spins, and provides superior control over the DNP efficiency under MAS. Experimental and quantum-mechanics based numerically simulated results together demonstrate that FAB-DNP significantly outperforms CW-DNP when the EPR-line of PAs is broadened by conformational distribution and exchange coupling. We demonstrate that the maximum benefit of FAB DNP is achieved when the electron spin-lattice relaxation is fast relative to the MAS frequency, i.e. at higher temperatures and/or when employing metals as PAs. Calculations predict that under short T<sub>1e </sub>conditions AWG-DNP can achieve as much as ~4-fold greater enhancement compared to CW-DNP.

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