skip to main content

Search for: All records

Creators/Authors contains: "Vijayan, Vineeth M."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Polydopamine-based bioinspired surface coating can augment improved adhesive nature and functional performance to materials. Here in, we report for the first time the capability of low-temperature hydrogen plasma treatment to enhance the polydopamine coating on 3D-Printed Polymer Scaffolds. The hydrogen plasma-treated scaffolds were systematically characterized with different analytical techniques. It was seen that hydrogen plasma treatment can significantly enhance the polydopamine coating on scaffolds. This observed finding of the utility of plasma to enhance the polydopa- mine coating on 3D-printed polymer scaffolds could significantly reduce the current processing time of polydopamine coating on material surfaces. 
    more » « less
    Free, publicly-accessible full text available July 28, 2024
  2. A microwave plasma chemical vapor deposition system was used to synthesize cubic boron nitride (cBN) coatings on diamond seeded silicon substrates using direct current (DC) bias. Effects of the argon (Ar) flow rate and bias voltage on the growth of the cBN coatings were investigated. Hydrogen (H2), argon (Ar), a mixture of diborane in H2 (95% H2, 5% B2H6), and N2 were used in the feed gas. A DC bias system was used for external biasing of the sample, which facilitates the goal of achieving sp3 bonded cBN. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) revealed the existence of sp3-bonded BN in the produced samples. With increasing Ar flow, the cBN content in the coating increases and reaches a maximum at the maximum Ar flow of 400 SCCM used in this study. High-resolution XPS scans for B1s and N1s indicate that the deposited coating contains more than 70% cBN. This study demonstrates that energetic argon ions generated in a microwave-induced plasma significantly increase cBN content in the coating. 
    more » « less
  3. Boron nitride (BN) is primarily a synthetically produced advanced ceramic material. It is isoelectronic to carbon and, like carbon, can exist as several polymorphic modifications. Microwave plasma chemical vapor deposition (MPCVD) of metastable wurtzite boron nitride is reported for the first time and found to be facilitated by the application of direct current (DC) bias to the substrate. The applied negative DC bias was found to yield a higher content of sp3 bonded BN in both cubic and metastable wurtzite structural forms. This is confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Nano-indentation measurements reveal an average coating hardness of 25 GPa with some measurements as high as 31 GPa, consistent with a substantial fraction of sp3 bonding mixed with the hexagonal sp2 bonded BN phase. 
    more » « less
  4. null (Ed.)
  5. null (Ed.)
  6. Theranostics is a recently emerging area in nanomedicine. Nanoparticles which can combineboth diagnostic and therapy in one single platform serve as theranostic agents. Some of the currentlyexplored nanoparticles are metallic nanoparticles, mesoporous silica nanoparticles, carbonbasednanoparticles, and polymer nanogels. Polymeric nanogels are receiving considerable attentiondue to their high biocompatibility and functional performance. The present review article brieflysummarizes the scopes and challenges of the state of art of using polymeric nanogels for theranosticapplications. Among the different polymer nanogels, a special emphasis is given to polymeric nanogelswith innate imaging potential. 
    more » « less
  7. null (Ed.)
    Superhard boron-rich boron carbide coatings were deposited on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) under controlled conditions, which led to either a disordered or crystalline structure, as measured by X-ray diffraction. The control of either disordered or crystalline structures was achieved solely by the choice of the sample being placed either directly on top of the sample holder or within an inset of the sample holder, respectively. The carbon content in the B-C bonded disordered and crystalline coatings was 6.1 at.% and 4.5 at.%, respectively, as measured by X-ray photoelectron spectroscopy. X-ray diffraction analysis of the crystalline coating provided a good match with a B50C2-type structure in which two carbon atoms replaced boron in the α-tetragonal B52 structure, or in which the carbon atoms occupied different interstitial sites. Density functional theory predictions were used to evaluate the dynamical stability of the potential B50C2 structural forms and were consistent with the measurements. The measured nanoindentation hardness of the coatings was as high as 64 GPa, well above the 40 GPa threshold for superhardness. 
    more » « less