Publications by authors named "Nuggehalli M Ravindra"

5 Publications

  • Page 1 of 1

Additive Manufacturing of Sensors for Military Monitoring Applications.

Polymers (Basel) 2021 Apr 30;13(9). Epub 2021 Apr 30.

Interdisciplinary Program in Materials Science and Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA.

The US Department of Defense (DoD) realizes the many uses of additive manufacturing (AM) as it has become a common fabrication technique for an extensive range of engineering components in several industrial sectors. 3D Printed (3DP) sensor technology offers high-performance features as a way to track individual warfighters on the battlefield, offering protection from threats such as weaponized toxins, bacteria or virus, with real-time monitoring of physiological events, advanced diagnostics, and connected feedback. Maximum protection of the warfighter gives a distinct advantage over adversaries by providing an enhanced awareness of situational threats on the battle field. There is a need to further explore aspects of AM such as higher printing resolution and efficiency, with faster print times and higher performance, sensitivity and optimized fabrication to ensure that soldiers are more safe and lethal to win our nation's wars and come home safely. A review and comparison of various 3DP techniques for sensor fabrication is presented.
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http://dx.doi.org/10.3390/polym13091455DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8125590PMC
April 2021

Hydrophobically Modified Isosorbide Dimethacrylates as a Bisphenol-A (BPA)-Free Dental Filling Material.

Materials (Basel) 2021 Apr 22;14(9). Epub 2021 Apr 22.

Interdisciplinary Program in Materials Science and Engineering, New Jersey Institute of Technology, Newark, NJ 07012, USA.

A series of bio-based hydrophobically modified isosorbide dimethacrylates, with , , and benzoate aromatic spacers (ISBGBMA), are synthesized, characterized, and evaluated as potential dental restorative resins. The new monomers, isosorbide 2,5-bis(4-glyceryloxybenzoate) dimethacrylate (ISB4GBMA), isosorbide 2,5-bis(3-glyceryloxybenzoate) dimethacrylate (ISB3GBMA), and isosorbide 2,5-bis(2-glyceryloxybenzoate) dimethacrylate (ISB2GBMA), are mixed with triethylene glycol dimethacrylate (TEGDMA) and photopolymerized. The resulting polymers are evaluated for the degree of monomeric conversion, polymerization shrinkage, water sorption, glass transition temperature, and flexural strength. Isosorbide glycerolate dimethacrylate (ISDGMA) is synthesized, and Bisphenol A glycerolate dimethacrylate (BisGMA) is prepared, and both are evaluated as a reference. Poly(ISBGBMA/TEGDMA) series shows lower water sorption (39-44 µg/mm) over Poly(ISDGMA/TEGDMA) (73 µg/mm) but higher than Poly(BisGMA/TEGDMA) (26 µg/mm). Flexural strength is higher for Poly(ISBGBMA/TEGDMA) series (37-45 MPa) over Poly(ISDGMA/TEGDMA) (10 MPa) and less than Poly(BisGMA/TEGDMA) (53 MPa) after immersion in phosphate-buffered saline (DPBS) for 24 h. Poly(ISB2GBMA/TEGDMA) has the highest glass transition temperature at 85 °C, and its monomeric mixture has the lowest viscosity at 0.62 Pa·s, among the (ISBGBMA/TEGDMA) polymers and monomer mixtures. Collectively, this data suggests that the ortho ISBGBMA monomer is a potential bio-based, BPA-free replacement for BisGMA, and could be the focus for future study.
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http://dx.doi.org/10.3390/ma14092139DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8122847PMC
April 2021

Energy Gap-Refractive Index Relations in Perovskites.

Materials (Basel) 2020 Apr 19;13(8). Epub 2020 Apr 19.

Interdisciplinary Program in Materials Science & Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA.

In this study, the energy gap-refractive index relations of perovskites are examined in detail. In general, the properties of perovskites are dependent on the structural reorganization and covalent nature of their octahedral cages. Based on this notion, a simple relation governing the energy gap and the refractive index is proposed for perovskites. The results obtained with this relation are in good accord with the literature values and are consistent with some well-established relations.
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http://dx.doi.org/10.3390/ma13081917DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7215549PMC
April 2020

A Magnetic-Field-Assisted Milli-Scale Robotic Assembly Machine: An Approach to Parallel Robotic Automation Systems.

Micromachines (Basel) 2018 Mar 23;9(4). Epub 2018 Mar 23.

Interdisciplinary Program in Materials Science & Engineering, New Jersey Institute of Technology, 323 Dr Martin Luther King Jr Blvd, Newark, NJ 07102, USA.

Utilizing large numbers of microrobots to heterogeneously integrate small devices to build advanced structures has long been a goal in the field of manufacturing automation. In this paper, we demonstrate a novel milli-scale robotic assembly machine with highly parallel capabilities and assisted with a programmable magnetic field. The prototype machine consists of a 16 × 16 array of electromagnets. Using this machine, we have successfully demonstrated the manipulation of up to nine milli-scale robots simultaneously. Moreover, two microrobots have been operated to demonstrate the proof of concept of two simultaneous pick-and-place light-emitting diodes (LEDs). The design and modeling of the microrobots is discussed.
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http://dx.doi.org/10.3390/mi9040144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6187365PMC
March 2018

Multi-pass Monte Carlo simulation method in nuclear transmutations.

Appl Radiat Isot 2016 Dec 21;118:211-214. Epub 2016 Sep 21.

New Jersey Institute of Technology, United States.

Monte Carlo methods, in their direct brute simulation incarnation, bring realistic results if the involved probabilities, be they geometrical or otherwise, remain constant for the duration of the simulation. However, there are physical setups where the evolution of the simulation represents a modification of the simulated system itself. Chief among such evolving simulated systems are the activation/transmutation setups. That is, the simulation starts with a given set of probabilities, which are determined by the geometry of the system, the components and by the microscopic interaction cross-sections. However, the relative weight of the components of the system changes along with the steps of the simulation. A natural measure would be adjusting probabilities after every step of the simulation. On the other hand, the physical system has typically a number of components of the order of Avogadro's number, usually 10 or 10 members. A simulation step changes the characteristics for just a few of these members; a probability will therefore shift by a quantity of 1/10. Such a change cannot be accounted for within a simulation, because then the simulation should have then a number of at least 10 steps in order to have some significance. This is not feasible, of course. For our computing devices, a simulation of one million steps is comfortable, but a further order of magnitude becomes too big a stretch for the computing resources. We propose here a method of dealing with the changing probabilities, leading to the increasing of the precision. This method is intended as a fast approximating approach, and also as a simple introduction (for the benefit of students) in the very branched subject of Monte Carlo simulations vis-à-vis nuclear reactors.
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http://dx.doi.org/10.1016/j.apradiso.2016.09.019DOI Listing
December 2016
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