Umesh P. Agarwal

Current research interests are extended in a number of areas. The focus is on both applied and fundamental investigations. One of the areas of focus is production, characterization, and applications of nanocelluloses. Understanding cellulose-crystallinity and cellulose supramolecular structure is yet another area that will have impact on several areas of research in the field of biomass, e.g., biofuels/biorefinery, nanocelluloses, and wood products. Advances in the understanding of wood cell wall nanostructure will permit better understanding of the complex ultrastructural interactions incorporating cellulose nanofibril, hemicellulose and lignin. Past and ongoing Raman spectroscopy research at FPL has made it possible to obtain useful information when cellulose and lignin-based materials are analyzed. Such analysis can now be carried out both at macro- and sub-micron levels (confocal Raman mapping). For determining the crystallinities of nano-celluloses and other cellulose containing materials, including wood, development of new methods based on Raman spectroscopy is an active area of research. For lignin analysis, new advancements in applying Raman spectroscopy are being made that permit new information to be obtained. Development and utilization of Raman spectroscopy for characterization of cellulose nanomaterials and their composites is another area of activity. Lastly, in the pulp and paper field, an area of interest is understanding hornification of pulp fibers and finding a solution for this problem. Agarwal, Umesh P.; Ralph, Sally A.; Baez, Carlos; Reiner, Richard S. 2021. Contributions of Crystalline and Noncrystalline Cellulose Can Occur in the Same Spectral Regions: Evidence Based on Raman and IR and Its Implication for Crystallinity Measurements.

References:
Biomacromolecules. 22(4): 1357-1373. https://doi.org/10.1021/acs.biomac.0c01389.
Agarwal, Umesh P.; Reiner, Richard S.; Ralph, Sally A.; Catchmark, Jeffery; Chi, Kai; Foster, E. Johan; Hunt, Christopher G.; Baez, Carlos; Ibach, Rebecca E.; Hirth, Kolby C. 2021. Characterization of the supramolecular structures of cellulose nanocrystals of different origins. Cellulose. 28(3): 1369-1385. https://doi.org/10.1007/s10570-020-03590-z.

• Understanding cellulose crystallinity and cellulose supramolecular structure
• Methods for estimating crystallinity of cellulose containing materials
• Nanocelluloses: production, characterization, and applications
• Nanostructure of wood cell wall
• Advancing applications of Raman spectroscopy for characterization of woody biomass and its components
• Utilization of woody biomass

References:
Agarwal, Umesh P.; Ralph, Sally A.; Padmakshan, Dharshana; Liu, Sarah; Foster, Cliff E. 2019. Estimation of syringyl units in wood lignins by FT-Raman spectroscopy. Journal of Agricultural and Food Chemistry. 67(15): 4367-4374.

Agarwal, Umesh P.; Ralph, Sally A.; Baez, Carlos; Reiner, Richard S. 2021. Contributions of Crystalline and Noncrystalline Cellulose Can Occur in the Same Spectral Regions: Evidence Based on Raman and IR and Its Implication for Crystallinity Measurements. Biomacromolecules. 22(4): 1357-1373. https://doi.org/10.1021/acs.biomac.0c01389.

Agarwal, Umesh P.; Reiner, Richard S.; Ralph, Sally A.; Catchmark, Jeffery; Chi, Kai; Foster, E. Johan; Hunt, Christopher G.; Baez, Carlos; Ibach, Rebecca E.; Hirth, Kolby C. 2021. Characterization of the supramolecular structures of cellulose nanocrystals of different origins. Cellulose. 28(3): 1369-1385. https://doi.org/10.1007/s10570-020-03590-z.

Understanding cellulose crystallinity and cellulose supramolecular structure: Crystallinity has an important effect on the physical, mechanical, and chemical properties of celluloses and cellulose products. Raman spectroscopy has become an important analytical technique for nondestructive, qualitative, and quantitative analysis of cellulose-containing materials and is being increasingly used. Recent research performed in the scientist's group has shown it is possible to develop Raman spectroscopy-based methods to accurately estimate crystallinity of plant-based materials. However, further research is needed to fully develop this approach and address a number of remaining issues. Similarly, in various materials, better understanding of cellulose supramolecular structure will permit improved control of the processes for its modification.

Production, characterization and applications of nanocelluloses: Cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs) are important new materials in field of cellulose science and technology. These materials have generated remarkable excitement in the scientific community. The materials have unique physicochemical properties and are being used in many applications, e.g., as reinforcing components in nanocomposites.

Wood cell wall nanostructure: The problem of composition and architecture of wood cell wall is an important research topic and efforts over the years have revealed that the ultrastructure is complex and remains inadequately understood. The research objectives of the project “understanding the nanostructure of the wood cell wall” consist of (1) characterizing, non-invasively, plant cell wall in a number of tissue types, at the molecular level using Raman mapping and (2) understanding distribution and organization of lignin and cellulose in various morphological regions of woody tissues. The findings are expected to have important implications for several areas of research. A few examples of where such information may be of significance are, “structure-property relationships of cell-wall and wood-fiber”, “lignin biosynthesis and topochemistry”, and “deconstruction of plant cell walls” (where the recalcitrance of plant biomass to degradation is a function of how polymers crosslink and aggregate within walls).

Understanding roles of lignin and cellulose-crystallinity in enzyme hydrolysis of wood: For the conversion of wood to ethanol, the enzymatic hydrolysis of cellulose via glucose and fermentation is one of the most practical approaches and therefore, is an important area of research. Cellulose and lignin are essential components of wood but due to the inaccessibility of cellulose to enzymes within the complex cell wall matrix cellulose is not easily hydrolyzed. In addition to accessibility to cellulose its crystallinity remains an issue. Therefore, effects of cellulose crystallinity and lignin removal are two factors important that need to be the focus of investigation.

Advancing applications of Raman spectroscopy for characterization of woody biomass and its components: Although a number of Raman techniques have been used to study wood cell wall, lignin, and cellulose, this work is far from complete. Not only, additional methods need to be developed to accomplish specific tasks (e.g., estimation of crystallinity), but also spectral information obtained needs to be further interpreted. In this context, in relation to lignin, Raman database of lignin model compounds was developed and used in the interpretation Raman spectra of lignins. The objective continues to be developing a Raman database of lignin model compounds which is helpful for further interpretation and classification of spectra of lignins and/or lignocellulosics. Such information is deemed essential for analyzing the spectra of woods and other lignin containing materials.