Green synthesis has gained a wide recognition as clean synthesis technique in the recent years. In the present investigation, silver nanoparticles were prepared by a novel green synthesis technique using Mangifera indica (Mango leaves) and found to be successfully used in dental applications. The prepared samples were spectroscopically characterized by XRD, PSA, SEM with EDS, and UV–Vis spectroscopy. The crystalline size and lattice strain were analyzed from the XRD data which were counter-verified by W–H plots and particle size analyzer. The XRD peaks revealed that average crystalline size of the as-synthesized Ag nanoparticles was of 32.4 nm with face-centered cubic structure. This was counter-verified by particle size analyzer and Williamson–Hall plots and found to be 31.7 and 33.21 nm in the former and latter, and the crystalline size of Ag NPs could be concluded as 32 ± 2 nm. The morphological structure of the prepared sample was studied through SEM images and the chemical composition was analyzed by the EDS data. The band energy was calculated as 393 nm from UV–Vis, which confirmed the synthesized sample as Ag nanoparticles. To improve the mechanical bonding and hardness of the dentally used glass ionomer cement (GIC), the synthesized silver nanoparticles were incorporated into GIC in 2% weight ratio. The morphology of the prepared specimens was studied using optical microscope images. Vickers microhardness and Monsanto hardness tests were performed on GIC, GIC reinforced with microsilver particles and GIC reinforced with nanosilver particles and the latter derived a promising results. The results of the Monsanto tests confirmed the increase in hardness of the GIC reinforced with AgNps as 14.2 kg/cm2 compared to conventional GIC and GIC reinforced with silver microparticle as 11.7 and 9.5 kg/cm2. Similarly the Vickers hardness results exhibited the enhanced hardness of GIC-reinforced AgNps as 82 VHN compared to GIC as 54 and GIC-reinforced silver microparticles as 61 VHN. The antibacterial activity of AgNPs was tested by a well-diffusion method on Escherichia coli and Staphylococcus aureus bacteria, and the obtained results exhibited a promising antibacterial activity of the as-synthesized nanoparticles.
In this work, MoO3-CuO metal oxide composite nanopowders are prepared by simple mechanochemical assisted synthesis technique with the stoichiometric weight ratios of MoO3 and CuO as 2.3:1 and 3.3:1, respectively. The structural and spectroscopic properties of the as-synthesised samples are characterised by XRD, SEM with EDS, FT-IR, Raman spectroscopy and TGA/DTA. X-ray diffraction pattern demonstrates the peaks correspond to orthorhombic phase of α-MoO3 and monoclinic phase of β-CuO. The average crystalline sizes of the 2.3:1 and 3.3:1 samples were found to be 16 and 24 nm, respectively, which are supported by Williamson–Hall (W–H) calculations. The correlations between the milling rotational speeds with morphological characteristics are revealed by the SEM images. The fundamental modes of Mo=O and Cu–O were analysed by FT-IR. Raman analysis has provided the qualitative information about the structure of the mixed oxide composite. Thermogravimetry analysis and Differential Thermal Analysis (DTA) of MoO3-CuO have revealed that the dual phase mixed oxide composite is stable up to 709 °C with a negligible weight loss. Based on the above, it can be inferred that the synthesised mixed lubricous oxide nanocomposite could be used as a solid lubricant at elevated temperatures
In this work, we report the spectroscopic, thermal, and mechanical outcomes of epoxy reinforced sisal/flax (S/F) hybrid natural fiber composites. This work is intended to enhance the mechanical and thermal properties of the sisal fibers in addition of the flax fibers. In recent years, natural fiber composites gained inclusive credit as a supernumerary to conventional synthetic composites for their superior ecological properties. Five different varieties of composite slabs i.e., 60% epoxy matrix and 40% of sisal/flax fibers were fabricated unidirectionally through a simple hand layout method by varying sisal and flax ratio as (40/0, 30/10, 20/20, 10/30, and 0/40) with a constant weight fraction as 0.4Wf. The X-ray Diffraction analysis was performed on the 50S/50F specimen and the crystallinity index is calculated as 42.84%. The spectroscopic and thermal studies were conducted on the 50S/50F sample and the chemical imprint of the composite is revealed by the strong peaks of cellulose, hemicellulose, and lignin along with amorphous and crystalline content of the FTIR data and is confirmed through the XRD data. The addition of flax fibers to sisal fibers showed a constructive improvement of thermal stability which is shown by the TG/DTA graph. In a three-stage degradation of sample, a maximum is observed at 334oC. The tensile, flexural, and impact tests of all the fabricated composite samples are performed and ultimate tensile strength of 165.2 N/mm2 for the 40S/0F composite with an elongation of 9.2% is noted. The ultimate flexural stress of 8.1 N/mm2 is observed in composite 10S/30F and composite 10S/30F has an excellent ability to absorb impact force of 1.2J energy. Based on the above results the manufactured composites exhibited higher thermal and mechanical properties showing a unique characteristic for different concentrations of flax fibers. Thus, the developed composites can be used individually for various applications based on the requirement of the end-user.
Covid-19 remains a global pandemic surging with different variants like (Omicron) in various countries. An escalation in random testing for Covid-19 is considered as the golden standard by WHO to control the spread of Corona virus. RT-PCR and nucleic acid hybridization strategies are two highly sensitive outstanding tests used for the detection of SARS-CoV-2 in the DNA by the former and RNA/DNA by the later. Apart from the test for virus, antigen, and antibodies, other alternative hematological tests like CRP, Ferritine, IL-6, Blood Platelets and WBC, and plasma became essential for the detection and management of Covid-19. Overcoming the limitations of a rapid, efficient, low-cost, and easy-to-implement test kits are in imperative need to meet these requirements. Electrochemical sensors are considered as potential and ultrafast point-of-care sensors used as self-testing kits. In this work, we review the various modified electrodes with different nanomaterials such as graphene, CNTs, and nano-dopants used as electrochemical sensors in association with testing various different parameters for detection of covid-19. A detailed discussion on the merits of present testing patterns and scope of screen-printed electrochemical sensors modified with different nanomaterials and their advantages is presented.
The present work is intended to fabricate titanium diboride (TiB2) and yttrium oxide (Y2O3) fused bronze metal matrix composite by stir casting technique to achieve effective mechanical and corrosion properties. TiB2- Y2O3 nanocomposite powders were synthesized using the mechanical milling synthesis technique. Spectroscopic analyses like Powder X-Ray Diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM) were used to characterize the synthesized nanopowders. The XRD data revealed the average crystalline size of 110±5 nanometres with a hexagonal and cubic phase structure of TiB2 and Y2O3. The fundamental modes and other functional groups of the nanocomposite were analyzed using the FTIR analysis. The SEM images revealed the irregular morphological structures of the composite powders. The bronze metal matrix composite is fabricated by varying the weight percentage of TiB2-Y2O3 nanocomposite as 2%, 4%, and 6 wt.% with bronze alloy via stir casting technique. XRD graphs revealed the formation of metal matrix composite and the FESEM graphs revealed the porous morphology of the composite. The mechanical performance of the composite was analyzed by using the tensile, compression, and hardness tests. Specimen with 4% wt.% reinforcement material offered higher mechanical properties with 303 MPa tensile, 810 MPa compression, 141 HRB hardness, and good corrosion resistance. Hence the fabricated TiB2-Y2O3 fused bronze metal matrix composite with good mechanical and corrosion properties can be used for various sea environment applications.
Aim:The present work is aimed to evaluate and compare the metal-ceramic bond strength and clinical feasibility of three commercially available Ni-Cr alloys with different compositions before and after recasting. The hypothesis of this experiment is to evaluate the effect of the recasting of base metal alloys in the physical and chemical properties of alloys, which in turn affect the metal-ceramic bond strength. Materials and methods: In the present experiment, we considered 60 Ni-Cr metal samples, which were divided into group I and group II with every 30 samples. Group I consists of 30 samples fabricated with 100% new alloy, and group II consists of 30 samples fabricated with 100% recycled alloy. Groups I and II are further divided into three subgroups IA, IB, IC and IIA, IIB and IIC on the basis of three brands of Ni-Cr alloy as NDN as (A), soft alloy as (B) and superbond as (C) with each of 10 samples. Metal sprues and buttons obtained after casting of group I samples were used as a recast alloy for the fabrication of group II samples. Results: The flexural bond strength of the fabricated metal-ceramic samples was subjected to three points bending test in a universal testing machine. The obtained values were statistically analyzed using one-way analysis of variance and post hoc Tukey analysis. The morphological studies are the stereomicroscopic examination of all the samples revealed alloy-metal oxide disjunction failure. Conclusion:The mean flexural bond strength for all the groups was above the minimum requirement by American Dental Association (ADA) specification no. 38 and ISO specification 9693. The mean bond strength of group I samples is found to be greater than the group II samples. The soft alloy and superbond have the highest mean bonds when compared among the samples fabricated with 100% new alloy and 100% recycled alloy. Superbond and soft alloy are followed by former and later, and NDN is found to be least for both types. The soft alloy has more reduction in metal-ceramic bond strength in group II (samples fabricated with 100% recycled alloy) when compared to group I.
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