Intellectual Property and Publications
Here is a selection of my work throughout my career based on my scientific research in the form of peer-reviewed journal articles, patents, and conference papers.
November 15, 2021
The Mediterranean region encompasses three continents and a multitude of languages and forms of government. It is also remarkable that this part of the world contributed to the genesis and expansion of three of the world’s major organized religions. Despite minimal political integration, there is considerable overlap in terms of lifestyles, diets, climate, history of colonization, and cultural sensibilities between Mediterranean nations. These factors can be leveraged to improve sustainability outcomes, and with contextual data, develop new metrics and targeted and effective solutions for the region. However, before any metrology is created and adopted, there needs to be (1) an assessment of the types of avoided pollution which are a direct result of regional factors and circumstances that may not exist in North America and in Northern Europe where the majority of climate thought leadership is centered and (2) in light of those factors and circumstances, a re- evaluation of the effectiveness of sustainability practices adopted from outside the region.
Kombolias, M. Best Practices Versus Practices That Work: Rethinking Sustainability Strategies in the Mediterranean. GREEN 2021, Nov. 15, 2021, Athens, Greece.
January 30, 2020
Paper is a biphasic bio-composite material. The complexity of paper from a material science point of view is increased when it is manufactured for or used as a substrate in security printing products. However, most tests to evaluate such printing and graphic arts substrates are destructive and ex situ, resulting in a loss of information. Other tests may be non- destructive but may only provide visual assessments without any correlation to the chemical and physical properties of the substrate. There is a need to explore new metrologies which can interrogate security printing substrates in a non-destructive and contactless manner and yield data which corresponds to visual and physicochemical attributes. Resonant cavity dielectric spectroscopy provides a means to gather information on printing substrates derived from cellulose as well as those from synthetic polymers. In this paper, we provide four case studies demonstrating the broad utility of the resonant cavity dielectric spectroscopy technique in the analyses of unprinted substrates and surface modifications. The inherent forensic capabilities of this technique lend it well to further applications in secure document manufacturing.
Kombolias, M., Obrzut, J., Obeng, Y.S. Resonant Cavity Dielectric Spectroscopy for Quality Assurance Evaluations of Secure Documents. Optical Document Security 2020, Jan. 30, 2020, San Francisco, CA.
November 4, 2019
Current product composition and quality test methods for the paper and pulp industries are rooted in wet-bench chemistry techniques which cannot be used to distinguish between virgin and secondary fibers. We have recently demonstrated the application of an in situ and nondestructive assessment method based on dielectric spectroscopy (DS), which can address this deficiency in the testing of paper. The DS technique, which employs a resonant microwave cavity, could be applicable to quality assurance techniques such as gauge capability studies and real-time statistical process control (SPC), and may have inherent forensic capabilities. In this paper, we show how this DS technique can be used to distinguish between office copier paper products which may contain recycled fibers. We show a reasonable correlation between the dielectric characteristics (e.g., dielectric loss) and the atomistic level chemical changes that result from the paper recycling process.
Kombolias, M., Obrzut, J., Postek, M., Poster, D., Obeng, Y. Contactless Resonant Cavity Dielectric Spectroscopic Studies of Recycled Office Papers. Recycling. 2019, 4(4), 43; https://doi.org/10.3390/recycling4040043
October 4, 2019
The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.
Kombolias, M., Obrzut, J., Postek, M., Poster, D., Obeng, Y., Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper. J. Vis. Exp. (152) e59991, doi:10.3791/59991 (2019).
August 28, 2019
The current analytical techniques for characterizing printing and graphic arts substrates, particularly those used to date and authenticate provenance, are destructive. This limits the amount of data that can be captured from an individual sample. For samples being evaluated in forensic and archeological investigations, any loss or degradation of the materials is undesirable. Furthermore, it is difficult to produce statistically relevant data for such analytes. We have shown elsewhere that a contactless microwave resonant cavity dielectric spectroscopy technique can discriminate between paper samples made from different plant fiber species based on their lignin content. In this publication, we demonstrate the utility of the contactless resonant cavity dielectric spectroscopy (RCDS) technique in the characterization of naturally and artificially aged paper samples. Based on our experimental results, we suggest that the technique could be used in forensic and archeological investigations of unique paper products.
Kombolias, M., Obrzut, J., Postek, M., Poster, D., Obeng, S. Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper Aging. Analytical Letters. Aug. 28, 2019. DOI: 10.1080/00032719.2019.1655648
September 2018
Current product composition and quality test methods for the paper and pulp industry are mainly based on manual ex-situ wet-bench chemistry techniques. For example, the standard method for determining the furnish of paper, TAPPI T 401 “Fiber analysis of paper and paperboard,” relies on the experience and visual acuity of a specially trained analyst to determine the individual plant species present and to quantify the amount of each constituent fiber type in a sheet of paper. Thus, there is a need for a fast, nondestructive analytical technique that leverages intrinsic attributes of the analytes.
In this paper, we demonstrate an application of dielectric spectroscopy (DS) as a potential metrology to differentite between nonwood pulp and wood pulp fibers. This in-situ, noncontact and nondestructive assessment method has inherent forensic capabilities and is also amiable to quality assurance techniques such as gauge capability studies and real-time statistical process control (SPC).
Application: The dielectric spectroscopy results presented in this paper can nondestructively determine the amount of lignin in paper products and are in principle comparable to the performance specifications of the TAPPI Standard Test Method T 401. This DS method should enable the sources of printing substrates to be both authentiated and validated in real time in a paper testing laboratory environment.
Kombolias, M., Obrzut, J., Montgomery, K., Postek, M., Poster, D., Obeng, Y., Dielectric Spectroscopic Studies of Biological Material Evolution and Application to Paper. TAPPI Journal. 2018, 17(9), 501-505.
March 27, 2018
Systems and methods for determining adhesive strength
Embodiments of the invention include systems and methods for determining adhesive strength of a sample label. For example, the present invention relates to a novel approach for examining the resistance to peel force required to remove a pressure sensitive adhesive (PSA) label from its intended substrate. This approach is encompassed by systems and methods which rely on the creation of one or any combination of at least four test strip types traced and cut from a label adhered to its intended substrate. The test strips may be oriented in at least three ways: along the machine direction of the label's face stock, along the cross direction of the label's face stock, and along an angle diagonal to the intersection of the machine and cross directions of the label's face stock, where the angle does not equal 0°, 90°, 180°, 270°, or 360°. The test strips may be peeled in reference to the position along the label and to and from which they extend.
Kombolias, M. Systems and methods for determining adhesive strength. US Patent 9,927,337. Filed June 30, 2015. Issued March 27, 2018.
February 8, 2010
While it is commonly known that layered LixCoO2 transforms to a mixture of stoichiometric LiCoO2 and Co3O4 at elevated temperature, little experimental detail exists on the role time and temperature play in the transformation process or on the occurrence of possible intermediate phases. In this article we follow the thermal decomposition of LixCoO2 by characterizing its decomposition products after short and long-term isothermal annealing at 350 °C. X-ray diffraction and transition electron microscopy observations are complemented by electron energy loss spectroscopy and magnetic susceptibility measurements thus allowing the combination of structural and electronic information. Our results indicate that the charge balance upon Li extraction from LiCoO2 is in parts accomplished by oxidation of Co3+ to Co4+. In the annealed powder we observe an intermediate Li–Co–O phase of cubic spinel structure before the end products Co3O4 and CoO are formed.
Gabrisch, H.; Kombolias, M.; Mohanty, D. Thermal Decomposition of LixCoO2 Monitored by Electron Energy Loss Spectroscopy and Magnetic Susceptibility Measurements. Solid State Ionics. 2010, 181, 71-78.
September 28, 2007
LiCoO2 is used as a cathode material in most commercial lithium- ion batteries. Of the phases formed upon Li-removal the P3 phase has been only reported in the chemically delithiated materials. In this paper we compared LixCoO2 produced by chemical and electrochemical methods. P3 phase was found in both chemically and electrochemically delithiated specimens. We investigate the phases formed at elevated temperatures by X-ray diffraction and electron microscopy.
Yi, T.; Kombolias, M.; Gabrisch, H. Investigation of LixCoO2 Phases Produced by Heat Treatment of Delithiated LiCoO2 Powders. ECS Transactions. 2007, 3, 145-151.