Shiv Nadar University

About: Shiv Nadar University is a education organization based out in Dadri, Uttar Pradesh, India. It is known for research contribution in the topics: Population & Graphene. The organization has 1015 authors who have published 1924 publications receiving 18420 citations.

Towards highly durable bimodal composite claddings using microwave processing

Abstract: Bimodal composite structures conjugating both high hardness and fracture toughness can effectively counter erosion induced degradation. The present work successfully develops bimodal metal matrix composite claddings using facile and cost-effective microwave technique, exploiting the direct and effective coupling phenomenon of reinforcement with microwave irradiation. For comprehensiveness, unimodal micro-/nano-reinforced clads were also developed. Interestingly, unimodal micro-composite clad showed refined structure compared to nano counterpart which is due to the effective coupling of later with microwave irradiation causing particle dissociation into the matrix. Compared to unimodal claddings, bimodal showed the highest hardness and indentation fracture toughness. In addition to ex-situ reinforcements, intrinsically evolved secondary phases also effectively contributed towards improved mechanical properties. The better performance of the bimodal clad is related to reduced agglomeration and dissociation of the nanoparticles, refined microstructure and constructive interaction between micro and nano-reinforcements. The phenomenal mechanical properties of bimodal composite clad resulted in improved durability compared to unimodal composite claddings under different tribological test conditions.

Multifunctional reduced graphene oxide coated cloths for oil/water separation and antibacterial application

Abstract: Multifunctional reduced graphene oxide (RGO) coated cloths were prepared through the thermal treatment of GO coated cloths without using any harmful reducing agent. The effect of heating temperature on the wetting properties of the cloths was also monitored through contact angle measurement. The highest contact angle 141° was observed for the RGO coated dense cloth while the highest contact angle exhibited by the RGO coated sparse cloth was 130°. The as prepared RGO coated cloths were utilized as a filter and an absorbent for oil/water separation. The RGO coated sparse cloth was utilized as a filter for the separation of an oil/water mixture while the dense cloth was utilized as an absorbent for the selective absorption of oil from water. RGO coated cloths were also explored as an antibacterial agent and the effect of the microstructure of coated cloths on their antibacterial properties was also investigated. The cloth with the dense structure exhibited higher antibacterial activity compared to the sparse cloth. A significant loss of percentage viability up to 98% was achieved using the RGO coated cloth, proving it highly efficient as an antibacterial agent, which makes it a suitable bandage material for the dressing of open wounds. Apart from being antibacterial, the RGO coated cloths are also hydrophobic in nature so they can protect wound from water and atmospheric moisture which is not possible with ordinary bandages.

Facile synthesis of novel hydrophilic and carboxyl-amine functionalized superparamagnetic iron oxide nanoparticles for biomedical applications

Abstract: In this work, we aim to synthesize water soluble and surface functionalized superparamagnetic iron oxide nanoparticles (SPIONs) using novel surfactants such as terephthalic acid (TA), 2-aminoterephthalic acid (ATA), trimesic acid (TMA) and pyromellitic acid (PMA) through one-step facile chemical co-precipitation and thermal decomposition methods. The as-synthesized SPIONs are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS) measurements, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). The as-synthesized SPIONs showed very good water solubility and a high magnetization value (Ms = 55–73 emu g−1). Furthermore, the as-synthesized ATA-coated SPIONs are conjugated with a fluorophore (Alexa Fluor 488) to demonstrate their ability for further chemical/biological conjugation without any additional surface modifications. Moreover, above 90% cell viability in MCF-7 cancer cells has been observed, thus confirming good cytocompatibility of the SPIONs. Therefore, these hydrophilic and carboxyl-amine functionalized SPIONs are very promising candidates to be used for biomedical applications.

Growth behavior, electronic structure, and vibrational properties of Si n Y anion clusters ( n = 4–20): Metal atom as linker and endohedral dopant

Abstract: We report results of ab initio calculations on Y-doped anion Si${}_{n}$ clusters with $n$ $=$ 4--20. Our results suggest two growth behaviors in the intermediate range of $n$ $=$ 8 and 20: (1) There is the formation of linked clusters in which a metal atom links two subclusters and (2) where silicon atoms form a cage structure and the metal atom is inside the cage to produce endohedral cages of silicon clusters. The cluster structures have been identified by comparing the calculated spectra of the electronic states with the photoemission spectra on anion clusters. Our results suggest that in some cases a higher energy isomer may be present in experiments. We report the calculations of the infrared and Raman spectra as well as the dipole moments, electron affinity, and polarizability that could provide other ways of identifying the growth behavior in these clusters.