John A, Nychka

Dr. John A, Nychka

orcid

Research Focus & Metrics

Academic Career Length

22Years (2005-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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12 February 2013 in Journal of the American Ceramic Society
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Journal Article
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HPHamidreza Pirayesh
Hamidreza Pirayesh
JNJohn A, Nychka
John A, Nychka

24 June 2014 in Journal of Prosthodontics
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Journal Article
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SPSheila Pestana Passos
Sheila Pestana Passos
YTYsidora Torrealba
Ysidora Torrealba
PMPaul Major
Paul Major
BLBernie Linke
Bernie Linke
CFCarlos Flores-Mir
Carlos Flores-Mir
JNJohn A, Nychka
John A, Nychka

6 June 2012 in Biointerphases
Verified
Journal Article
Open access
MBMarkian S. Bahniuk
Markian S. Bahniuk
HPHamidreza Pirayesh
Hamidreza Pirayesh
HSHarsh D. Singh
Harsh D. Singh
JNJohn A, Nychka
John A, Nychka
LULarry Unsworth
Larry Unsworth
Despite its medical applications, the mechanisms responsible for the osseointegration of bioactive glass (45S5) have yet to be fully understood. Evidence suggests that the strongest predictor for osseointegration of bioactive glasses, and ceramics, with bone tissue as the formation of an apatitic calcium phosphate layer atop the implanted material, with osteoblasts being the main mediator for new bone formation. Most have tried to understand the formation of this apatitic calcium phosphate layer, and other bioresponses between the host and bioactive glass 45S5 using Simulated Body Fluid; a solution containing ion concentrations similar to that found in human plasma without the presence of proteins. However, it is likely that cell attachment is probably largely mediated via the adsorbed protein layer. Plasma protein adsorption at the tissue bioactive glass interface has been largely overlooked. Herein, we compare crystalline and amorphous bioactive glass 45S5, in both melt-derived as well as sol–gel forms. Thus, allowing for a detailed understanding of both the role of crystallinity and powder morphology on surface ions, and plasma protein adsorption. It was found that sol–gel 45S5 powders, regardless of crystallinity, adsorbed 3–5 times as much protein as the crystalline melt-derived counterpart, as well as a greater variety of plasma proteins. The devitrification of melt-cast 45S5 resulted in only small differences in the amount and variety of the adsorbed proteome. Surface properties, and not material crystallinity, play a role in directing protein adsorption phenomena for bioactive glasses given the differences found between crystalline melt-cast 45S5 and sol–gel derived 45S5.

19 August 2015 in ACS Applied Materials & Interfaces
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Journal Article
Open access
XLXinda Li
Xinda Li
YCYi Chen
Yi Chen
AKAmit Kumar
Amit Kumar
AMAhmed Mahmoud
Ahmed Mahmoud
JNJohn A, Nychka
John A, Nychka
Hyun-Joong ChungHyun-Joong Chung
Hyun-Joong Chung
We report a simple approach to fabricate zinc oxide (ZnO) nanowire based electricity generators on three-dimensional (3D) graphene networks by utilizing a commercial polyurethane (PU) sponge as a structural template. Here, a 3D network of graphene oxide is deposited from solution on the template and then is chemically reduced. Following steps of ZnO nanowire growth, polydimethylsiloxane (PDMS) backfilling and electrode lamination completes the fabrication processes. When compared to conventional generators with 2D planar geometry, the sponge template provides a 3D structure that has a potential to increase power density per unit area. The modified one-pot ZnO synthesis method allows the whole process to be inexpensive and environmentally benign. The nanogenerator yields an open circuit voltage of ∼0.5 V and short circuit current density of ∼2 μA/cm2, while the output was found to be consistent after ∼3000 cycles. Finite element analysis of stress distribution showed that external stress is concentrated to deform ZnO nanowires by orders of magnitude compared to surrounding PU and PDMS, in agreement with our experiment. It is shown that the backfilled PDMS plays a crucial role for the stress concentration, which leads to an efficient electricity generation.

1 September 2015 in Dental Materials
Verified
Journal Article
Closed access
SPSheila P. Passos
Sheila P. Passos
BLBernie Linke
Bernie Linke
PMPaul W. Major
Paul W. Major
JNJohn A, Nychka
John A, Nychka

17 April 2013 in Journal of Applied Polymer Science
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Journal Article
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NRNicole‐Lee M. Robertson
Nicole‐Lee M. Robertson
JNJohn A, Nychka
John A, Nychka
KAKirill Alemaskin
Kirill Alemaskin
JWJohn D. Wolodko
John D. Wolodko