Fabrication, structural, and enhanced mechanical behavior of MgO substituted PMMA composites for dental applications

The most common denture material used for dentistry is poly-methyl-methacrylate (PMMA). Usually, the polymeric PMMA material has numerous biological, mechanical and cost-effective shortcomings. Hence, to resolve such types of drawbacks, attempts have been made to investigate fillers of the PMMA like alumina (Al2O3), silica (SiO2), zirconia (ZrO2) etc. For the enhancement of the PMMA properties a suitable additive is required for its orthopedic applications. Herein, the main motive of this study was to synthesize a magnesium oxide (MgO) reinforced polymer-based hybrid nano-composites by using heat cure method with superior optical, biological and mechanical characteristics. For the structural and vibrational studies of the composites, XRD and FT-IR were carried out. Herein, the percentage of crystallinity for all the fabricated composites were also calculated and found to be 14.79-30.31. Various physical and optical parameters such as density, band gap, Urbach energy, cutoff energy, cutoff wavelength, steepness parameter, electron-phonon interaction, refractive index, and optical dielectric constant were also studied and their values are found to be in the range of 1.21-1.394 g/cm3, 5.44-5.48 eV, 0.167-0.027 eV, 5.68 eV, 218 nm, 0.156-0.962, 4.273-0.693, 1.937-1.932, and 3.752-3.731 respectively. To evaluate the mechanical properties like compressive strength, flexural strength, and fracture toughness of the composites a Universal Testing Machine (UTM) was used and their values were 60.3 and 101 MPa, 78 and 40.3 MPa, 5.85 and 9.8 MPa-m1/2 respectively. Tribological tests of the composites were also carried out. In order to check the toxicity, MTT assay was also carried out for the PM0 and PM15 [(x)MgO + (100 - x) (C5O2H8)n] (x = 0 and 15) composites. This study provides a comprehensive insight into the structural, physical, optical, and biological features of the fabricated PMMA-MgO composites, highlighting the potential of the PM15 composite with its enhanced density, mechanical strength, and excellent biocompatibility for denture applications.

Synergetic effects of boron nitride with waste zirconia: Evaluation of instantaneous fingerprint detection and mechanical properties for biomedical applications

Herein, present study mainly focuses on the synthesis and characterizations of boron nitride reinforced waste zirconia (wZrO2) with different concentrations. Composites were prepared via a scalable solid-state reaction method. Various physical parameters such as density, ionic concentration, polaron radius, and field strength were evaluated. XRD results reveal crystalline nature with a major phase of tetragonal zirconia and as boron nitride is reinforced, the tetragonal transforms into a monoclinic zirconia. Interconnected spherical grains and nanosheets were observed using FESEM. Mechanical characterizations revealed the highest compressive strength of 266 MPa. The latent fingerprints were visualized using a composite on different surfaces, implementing the powder dusting and solution techniques. MTT assay was performed and revealed good biocompatible nature. These results reveal that composite is suitable for fabrication of bioceramics with acceptable mechanical and biological performances. The composite can also be utilized for latent fingerprint detection in forensic science.

Recent Advances in Additive Manufacturing, Applications and Challenges for Dentistry: A Review

Technological advancement in the field of dentistry has to be proven in new avenues for professionals as well as laboratory programmers. An advanced type of technology is emerging based on digitalization, as a computerized three-dimensional (3-D) model, additive manufacturing also called 3-D printing, allows formation of block pieces by adding material layer-by-layer. The additive manufacturing (AM) approach has offered extreme progress in the broad choice of distinct zones, permitting the production of fragments of all possible varieties of substances such as metal, polymer, ceramic, and composites. The significant goal of current the article is to recapitulate the recent scenarios including the imminent perspective of AM techniques and challenges in dentistry. Moreover, this article reviews the recent developments of 3-D printing advancements along with the advantages and disadvantages. Herein, various AM technologies comprising vat photopolymerization (VPP), material jetting, material extrusion, selective laser sintering (SLS), selective laser melting (SLM), and direct metal laser sintering (DMLS) technologies based powder bed fusion technologies/direct energy deposition/sheet lamination centered on binder jetting technologies were discussed in detail. This paper attempts to provide a balanced view by emphasizing the economic, scientific, and technical challenges and presenting an overview of methods to discuss the similarities based on the authors' continuing research and development.

Effect of lockdown amid second wave of COVID-19 on environmental noise scenario of the megacity Delhi, India

This paper analyzes the impact of second wave of COVID-19 lockdown on environmental noise levels of 25 sites in Delhi city and compares the noise scenario during pre-lockdown, lockdown, and post-lockdown periods. The study utilized the noise monitoring data acquired from 25 real-time ambient noise monitoring stations, installed by the Delhi Pollution Control Committee, Delhi, at various sites throughout Delhi city. A significant reduction of up to 10 and 3 dB(A) in day and night equivalent noise levels, respectively, had been observed during the lockdown period as compared to the pre-lockdown and post-lockdown periods. The study also revealed that only nine sites, including four industrial and five commercial zone sites, complied with the ambient noise standards during lockdown period, and no silence or residential zone sites complied with the ambient noise standards even during the lockdown period. A roadmap for environmental noise management and control is suggested. The study also reports the community's perception toward the change in acoustic environment of Delhi city during the lockdown period by conducting an environmental noise perception survey. The present study should be helpful in devising noise control action plans and policy interventions for environmental noise management and control in the metropolitan city Delhi, India.

Synthesis of a porous SiO2–H3BO3–V2O5–P2O5 glassy composite: structural and surface morphological behaviour for CO2 gas sensing applications

The present work mainly focuses on the fabrication of a porous glass 40SiO₂–35H₃BO₃–19V₂O₅–6P₂O₅via a melt-quenching technique. The structural, morphological, and sensing behaviour of the glass sample was investigated successfully. The calculated density and molar volume of the fabricated glass are 2.4813 ± 0.124 g cm⁻³ and 35.7660 ± 1.708 cm³ mol⁻¹. XRD, SEM and TEM analyses confirmed the amorphous nature of the glass. FTIR results revealed the O–H bond formations, which indicate that the presence of water molecules is probably due to the porous nature of the glass. Further, BET analysis confirmed the mesoporous nature of the glass sample with a mean pore diameter of 7 nm. The sensing response of the synthesized glass at 1000 ppm concentration of CO₂ was found to be 3.05 with a response time 22.6 s and recovery time 25.8 s. Hence, this porous glass can be easily synthesized, is affordable, and was found to be useful for CO₂ gas sensing applications.

The present work mainly focuses on the fabrication of a porous glass 40SiO₂–35H₃BO₃–19V₂O₅–6P₂O₅via a melt-quenching technique.

Methods of hexagonal boron nitride exfoliation and its functionalization: covalent and non-covalent approaches

The exfoliation of two-dimensional (2D) hexagonal boron nitride nanosheets (h-BNNSs) from bulk hexagonal boron nitride (h-BN) materials has received intense interest owing to their fascinating physical, chemical, and biological properties. Numerous exfoliation techniques offer scalable approaches for harvesting single-layer or few-layer h-BNNSs. Their structure is very comparable to graphite, and they have numerous significant applications owing to their superb thermal, electrical, optical, and mechanical performance. Exfoliation from bulk stacked h-BN is the most cost-effective way to obtain large quantities of few layer h-BN. Herein, numerous methods have been discussed to achieve the exfoliation of h-BN, each with advantages and disadvantages. Herein, we describe the existing exfoliation methods used to fabricate single-layer materials. Besides exfoliation methods, various functionalization methods, such as covalent, non-covalent, and Lewis acid-base approaches, including physical and chemical methods, are extensively described for the preparation of several h-BNNS derivatives. Moreover, the unique and potent characteristics of functionalized h-BNNSs, like enhanced solubility in water, improved thermal conductivity, stability, and excellent biocompatibility, lead to certain extensive applications in the areas of biomedical science, electronics, novel polymeric composites, and UV photodetectors, and these are also highlighted.

Retraction of "Fabrication of Graphene Nanoplatelet-Incorporated Porous Hydroxyapatite Composites: Improved Mechanical and in Vivo Imaging Performances for Emerging Biomedical Applications"

[This retracts the article DOI: 10.1021/acsomega.8b03473.].

Enhanced mechanical properties of hBN-ZrO2 composites and their biological activities on Drosophila melanogaster: synthesis and characterization

In this study, six compositions in the system [x(h-BN)-(100 - x)ZrO2] (10 ≤ x ≤ 90) were synthesized by a bottom up approach, i.e., the solid-state reaction technique. XRD results showed the formation of a novel and main phase of zirconium oxynitrate ZrO(NO3)2 and SEM exhibited mixed morphology of layered and stacked h-BN nanosheets with ZrO2 grains. The composite sample 10 wt% h-BN + 90 wt% ZrO2 (10B90Z) showed outstanding mechanical properties for different parameters, i.e., density (3.12 g cm-3), Young's modulus (10.10 GPa), toughness (2.56 MJ m-3), and maximum mechanical strength (227.33 MPa). The current study further checked the in vivo toxicity of composite 10B90Z and composite 90B10Z using Drosophila melanogaster. The composite 10B90Z showed less cytotoxicity in this model, while the composite 90B10Z showed higher toxicity in terms of organ development as well as internal damage of the gut mostly at the lower concentrations of 1, 10, and 25 μg mL-1. Altogether, the current study proposes the composite 10B90Z as an ideal compound for applications in biomedical research. This composite 10B90Z displays remarkable mechanical and biological performances, due to which we recommend this composition for various biomedical applications.

Fabrication of Graphene Nanoplatelet-Incorporated Porous Hydroxyapatite Composites: Improved Mechanical and in Vivo Imaging Performances for Emerging Biomedical Applications

Three-dimensional nanocomposites exhibit unexpected mechanical and biological properties that are produced from two-dimensional graphene nanoplatelets and oxide materials. In the present study, various composites of microwave-synthesized nanohydroxyapatite (nHAp) and graphene nanoparticles (GNPs), (100 - x)HAp-xGNPs (x = 0, 0.1, 0.2, 0.3, and 0.5 wt %), were successfully synthesized using a scalable bottom-up approach, that is, a solid-state reaction method. The structural, morphological and mechanical properties were studied using various characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and universal testing machine (UTM). XRD studies revealed that the prepared composites have high-order crystallinity. Addition of GNPs into nHAp significantly improved the mechanical properties. Three-dimensional nanocomposite 99.5HAp-0.5GNPs exhibited exceptionally high mechanical properties, for example, a fracture toughness of ∼116 MJ/m³, Young's modulus of ∼98 GPa, and compressive strength of 96.04 MPa, which were noticed to be much greater than in the pure nHAp. The MTT assay and cell imaging behaviors were carried out on the gut tissues of Drosophila third instars larvae and on primary rat osteoblast cells for the sample 99.5HAp-0.5GNPs that have achieved the highest mechanical properties. The treatment with lower concentrations of 10 μg/mL on the gut tissues of Drosophila and 1 and 5 μg/mL of this composite sample showed favorable cell viability. Therefore, owing to the excellent porous nature, interconnected surface morphology, and mechanical and biological properties, the prepared composite sample 99.5HAp-0.5GNPs stood as a promising biomaterial for bone implant applications.

Fabrication of Graphene Nanoplatelet-Incorporated Porous Hydroxyapatite Composites: Improved Mechanical and in Vivo Imaging Performances for Emerging Biomedical Applications

Three-dimensional nanocomposites exhibit unexpected mechanical and biological properties that are produced from two-dimensional graphene nanoplatelets and oxide materials. In the present study, various composites of microwave-synthesized nanohydroxyapatite (nHAp) and graphene nanoparticles (GNPs), (100 - x)HAp-xGNPs (x = 0, 0.1, 0.2, 0.3, and 0.5 wt %), were successfully synthesized using a scalable bottom-up approach, that is, a solid-state reaction method. The structural, morphological and mechanical properties were studied using various characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and universal testing machine (UTM). XRD studies revealed that the prepared composites have high-order crystallinity. Addition of GNPs into nHAp significantly improved the mechanical properties. Three-dimensional nanocomposite 99.5HAp-0.5GNPs exhibited exceptionally high mechanical properties, for example, a fracture toughness of ∼116 MJ/m3, Young's modulus of ∼98 GPa, and compressive strength of 96.04 MPa, which were noticed to be much greater than in the pure nHAp. The MTT assay and cell imaging behaviors were carried out on the gut tissues of Drosophila third instars larvae and on primary rat osteoblast cells for the sample 99.5HAp-0.5GNPs that have achieved the highest mechanical properties. The treatment with lower concentrations of 10 μg/mL on the gut tissues of Drosophila and 1 and 5 μg/mL of this composite sample showed favorable cell viability. Therefore, owing to the excellent porous nature, interconnected surface morphology, and mechanical and biological properties, the prepared composite sample 99.5HAp-0.5GNPs stood as a promising biomaterial for bone implant applications.

Synthesis and 3D Interconnected Nanostructured h-BN-Based Biocomposites by Low-Temperature Plasma Sintering: Bone Regeneration Applications

Recent advances and demands in biomedical applications drive a large amount of research to synthesize easily scalable low-density, high-strength, and wear-resistant biomaterials. The chemical inertness with low density combined with high strength makes h-BN one of the promising materials for such application. In this work, three-dimensional hexagonal boron nitride (h-BN) interconnected with boron trioxide (B₂O₃) was prepared by easily scalable and energy efficient spark plasma sintering (SPS) process. The composite structure shows significant densification (1.6-1.9 g/cm³) and high surface area (0.97-14.5 m²/g) at an extremely low SPS temperature of 250 °C. A high compressive strength of 291 MPa with a reasonably good wear resistance was obtained for the composite structure. The formation of strong covalent bonds between h-BN and B₂O₃ was formulated and established by molecular dynamics simulation. The composite showed significant effect on cell viability/proliferation. It shows a high mineralized nodule formation over the control, which suggests its use as a possible osteogenic agent in bone formation.

Synthesis and porous h-BN 3D architectures for effective humidity and gas sensors

3D (three dimensional) architectures synthesised using an easily scalable solid state method which results in an interconnected network of porous h-BN sheets with boron trioxide are reported in this study.

Zirconia based dental ceramics: structure, mechanical properties, biocompatibility and applications

Zirconia (ZrO₂) based dental ceramics have been considered to be advantageous materials with adequate mechanical properties for the manufacturing of medical devices.

Enhanced supercapacitor performance of a 3D architecture tailored using atomically thin rGO–MoS2 2D sheets

A stable, conductive, additive-free and scalable 3D architecture supercapacitor electrode fabricated by atomically thin 2D sheets of GO and MoS₂ shows superior electrochemical properties which are further substantiated using MD simulations.

Synthesis of Low-Density, Carbon-Doped, Porous Hexagonal Boron Nitride Solids

Here, we report the scalable synthesis and characterization of low-density, porous, three-dimensional (3D) solids consisting of two-dimensional (2D) hexagonal boron nitride (h-BN) sheets. The structures are synthesized using bottom-up, low-temperature (∼300 °C), solid-state reaction of melamine and boric acid giving rise to porous and mechanically stable interconnected h-BN layers. A layered 3D structure forms due to the formation of h-BN, and significant improvements in the mechanical properties were observed over a range of temperatures, compared to graphene oxide or reduced graphene oxide foams. A theoretical model based on Density Functional Theory (DFT) is proposed for the formation of h-BN architectures. The material shows excellent, recyclable absorption capacity for oils and organic solvents.

A Review on Infrared Spectroscopy of Borate Glasses with Effects of Different Additives

Borate glasses are the technologically important class of glasses and play a significant role in various applications. Borate glasses contain planar BO3 groups as structural units, rather than tetrahedral SiO4 groups. The oxygen atoms are, as in SiO2, again connected to two network-forming atoms, in case of boron. The radial distribution analysis describes the B2O3 glass structure as consisting of boroxol rings, that is, planar rings containing three boron atoms and three oxygen atoms. The network forming of the B2O3 and the SiO4 is affected with the addition of some metal cation additives Pb, Zn, Cd, and so forth. These additives also work as a network modifier and a nucleating agent for crystallization of glass. Therefore, the optical properties of the borate glasses have been changed significantly.