@misc{keshwani_cheng_2009, title={Switchgrass for bioethanol and other value-added applications: A review}, volume={100}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2008.09.035}, abstractNote={Switchgrass is a promising feedstock for value-added applications due to its high productivity, potentially low requirements for agricultural inputs and positive environmental impacts. The objective of this paper is to review published research on the conversion of switchgrass into bioethanol and other value-added products. Environmental benefits associated with switchgrass include the potential for carbon sequestration, nutrient recovery from runoff, soil remediation and provision of habitats for grassland birds. Pretreatment of switchgrass is required to improve the yields of fermentable sugars. Based on the type of pretreatment, glucose yields range from 70% to 90% and xylose yields range from 70% to 100% after hydrolysis. Following pretreatment and hydrolysis, ethanol yields range from 72% to 92% of the theoretical maximum. Other value-added uses of switchgrass include gasification, bio-oil production, newsprint production and fiber reinforcement in thermoplastic composites. Future prospects for research include increased biomass yields, optimization of feedstock composition for bioenergy applications, and efficient pentose fermentation to improve ethanol yields.}, number={4}, journal={BIORESOURCE TECHNOLOGY}, author={Keshwani, Deepak R. and Cheng, Jay J.}, year={2009}, month={Feb}, pages={1515–1523} } @inproceedings{wang_keshwani_redding_cheng_2008, title={Alkaline pretreatment of coastal bermudagrass for bioethanol production}, volume={084013}, booktitle={Proceedings of the ASABBE Annual International Meeting (Providence, Rhode Island)}, author={Wang, Z. and Keshwani, D. R. and Redding, A. P. and Cheng, J. J.}, year={2008} } @inproceedings{redding_wang_keshwani_cheng_2008, title={High temperature dilute acid pretreatment of coastal bermudagrass}, volume={084148}, DOI={10.13031/2013.25041}, abstractNote={The conversion of lignocellulosic biomass into ethanol is an encouraging technology in the face of concerns over global warming and finite energy resources. In the southeastern United States, coastal bermudagrass shows potential for use as an energy crop for ethanol production. A review of the literature has shown that research has been done on the dilute sulfuric acid pretreatment of costal bermudagrass at 121oC prior to enzymatic hydrolysis. This study examined dilute acid concentrations of 0.3%(w/w) to 1.2%(w/w) at temperatures from 120C to 180C over residence times of 5 to 60 minutes in an effort to optimize the pretreatment process for sugar production. Bermudagrass was pretreated in a 1:10 mixture with dilute sulfuric acid. The pretreated solids were enzymatically hydrolyzed and the resulting reducing sugars have been quantified using a DNS assay method. Data is still being generated,, but from average total reducing sugar data that has been analyzed, the pretreatment conditions of 1.2% sulfuric acid (w/w) for 30 minutes yields optimum sugar production of 300 mg sugars / gram of un-pretreated biomass. Carbohydrate and lignin content will be measured before and after pretreatment in addition to an estimation of reducing sugars in the pretreatment filtrate in future work.}, booktitle={Proceedings of the ASABE Annual International Meeting (Providence, Rhode Island)}, author={Redding, A. P. and Wang, Z. and Keshwani, D. R. and Cheng, Jay}, year={2008} } @inproceedings{keshwani_cheng_2008, title={Microwave-based alkali pretreatment of lignocelluloses}, booktitle={IBE Annual Meeting (Chapel Hill, North Carolina)}, author={Keshwani, D. R. and Cheng, J. J.}, year={2008} } @inproceedings{keshwani_cheng_2008, title={Modeling of microwave based chemical pretreatment of switchgrass}, volume={083954}, booktitle={Proceedings of the ASABE Annual International Meeting (Providence, Rhode Island)}, author={Keshwani, D. R. and Cheng, J. J.}, year={2008} } @article{keshwani_jones_meyer_brand_2008, title={Rule-based Mamdani-type fuzzy modeling of skin permeability}, volume={8}, ISSN={["1568-4946"]}, DOI={10.1016/j.asoc.2007.01.007}, abstractNote={Two Mamdani type fuzzy models (three inputs–one output and two inputs–one output) were developed to predict the permeability of compounds through human skin. The models were derived from multiple data sources including laboratory data, published data bases, published statistical models, and expert opinion. The inputs to the model include information about the compound (molecular weight and octonal–H2O partition coefficient) and the application temperature. One model included all three parameters as inputs and the other model only included information about the compound. The values for mole molecular weight ranged from 30 to 600 Da. The values for the log of the octonal–H2O partition coefficient ranged from −3.1 to 4.34. The values for the application temperature ranged from 22 to 39 °C. The predicted values of the log of permeability coefficient ranged from −5.5 to −0.08. Each model was a collection of rules that express the relationship of each input to the permeability of the compound through human skin. The quality of the model was determined by comparing predicted and actual fuzzy classification and defuzzification of the predicted outputs to get crisp values for correlating estimates with published values. A modified form of the Hamming distance measure is proposed to compare predicted and actual fuzzy classification. An entropy measure is used to describe the ambiguity associated with the predicted fuzzy outputs. The three input model predicted over 70% of the test data within one-half of a fuzzy class of the published data. The two input model predicted over 40% of the test data within one-half of a fuzzy class of the published data. Comparison of the models show that the three input model exhibited less entropy than the two input model.}, number={1}, journal={APPLIED SOFT COMPUTING}, author={Keshwani, Deepak R. and Jones, David D. and Meyer, George E. and Brand, Rhonda M.}, year={2008}, month={Jan}, pages={285–294} } @inproceedings{keshwani_cheng_li_burns_chiang_2007, title={Microwave pretreatment of switchgrass to enhance enzymatic hydrolysis}, volume={077127}, DOI={10.13031/2013.23472}, abstractNote={Switchgrass is a promising lignocellulosic biomass for fuel-ethanol production. However, pretreatment of lignocellulosic materials is necessary to improve its susceptibility to enzymatic hydrolysis. The objectives of this study were to examine the feasibility of microwave pretreatment to enhance enzymatic hydrolysis of switchgrass and to determine the optimal pretreatment conditions. Switchgrass samples immersed in water, dilute sulfuric acid and dilute sodium hydroxide solutions were exposed to microwave radiation at varying levels of radiation power and residence time. Pretreated solids were enzymatically hydrolyzed and reducing sugars in the hydrolysate were analyzed. Microwave radiation of switchgrass at lower power levels resulted in more efficient enzymatic hydrolysis. The application of microwave radiation for 10 minutes at 250 watts to switchgrass immersed in 3% sodium hydroxide solution (w/v) produced the highest yields of reducing sugar. Results were comparable to conventional 60 minute sodium hydroxide pretreatment of switchgrass. The findings suggest that combined microwave-alkali is a promising pretreatment method to enhance enzymatic hydrolysis of switchgrass.}, booktitle={Proceedings of the ASABE Annual International Meeting (Minneapolis, Minnesota)}, author={Keshwani, D. R. and Cheng, J. J. and Li, L. and Burns, J. C. and Chiang, V.}, year={2007} } @article{chen_sharma-shivappa_keshwani_chen_2007, title={Potential of agricultural residues and hay for bioethanol production}, volume={142}, ISSN={["1559-0291"]}, DOI={10.1007/s12010-007-0026-3}, abstractNote={Production of bioethanol from agricultural residues and hays (wheat, barley, and triticale straws, and barley, triticale, pearl millet, and sweet sorghum hays) through a series of chemical pretreatment, enzymatic hydrolysis, and fermentation processes was investigated in this study. Composition analysis suggested that the agricultural straws and hays studied contained approximately 28.62-38.58% glucan, 11.19-20.78% xylan, and 22.01-27.57% lignin, making them good candidates for bioethanol production. Chemical pretreatment with sulfuric acid or sodium hydroxide at concentrations of 0.5, 1.0, and 2.0% indicated that concentration and treatment agent play a significant role during pretreatment. After 2.0% sulfuric acid pretreatment at 121 degrees C/15 psi for 60 min, 78.10-81.27% of the xylan in untreated feedstocks was solubilized, while 75.09-84.52% of the lignin was reduced after 2.0% sodium hydroxide pretreatment under similar conditions. Enzymatic hydrolysis of chemically pretreated (2.0% NaOH or H2SO4) solids with Celluclast 1.5 L-Novozym 188 (cellobiase) enzyme combination resulted in equal or higher glucan and xylan conversion than with Spezyme(R) CP- xylanase combination. The glucan and xylan conversions during hydrolysis with Celluclast 1.5 L-cellobiase at 40 FPU/g glucan were 78.09 to 100.36% and 74.03 to 84.89%, respectively. Increasing the enzyme loading from 40 to 60 FPU/g glucan did not significantly increase sugar yield. The ethanol yield after fermentation of the hydrolyzate from different feedstocks with Saccharomyces cerevisiae ranged from 0.27 to 0.34 g/g glucose or 52.00-65.82% of the theoretical maximum ethanol yield.}, number={3}, journal={APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY}, author={Chen, Ye and Sharma-Shivappa, Ratna R. and Keshwani, Deepak and Chen, Chengci}, year={2007}, month={Sep}, pages={276–290} } @misc{keshwani_jones_brand_2005, title={Takagi-Sugeno fuzzy modeling of skin permeability}, volume={24}, ISSN={["1556-9535"]}, DOI={10.1080/15569520500278690}, abstractNote={ABSTRACT The skin is a major exposure route for many potentially toxic chemicals. It is, therefore, important to be able to predict the permeability of compounds through skin under a variety of conditions. Available skin permeability databases are often limited in scope and not conducive to developing effective models. This sparseness and ambiguity of available data prompted the use of fuzzy set theory to model and predict skin permeability. Using a previously published database containing 140 compounds, a rule-based Takagi–Sugeno fuzzy model is shown to predict skin permeability of compounds using octanol-water partition coefficient, molecular weight, and temperature as inputs. Model performance was estimated using a cross-validation approach. In addition, 10 data points were removed prior to model development for additional testing with new data. The fuzzy model is compared to a regression model for the same inputs using both R2 and root mean square error measures. The quality of the fuzzy model is also compared with previously published models. The statistical analysis demonstrates that the fuzzy model performs better than the regression model with identical data and validation protocols. The prediction quality for this model is similar to others that were published. The fuzzy model provides insights on the relationships between lipophilicity, molecular weight, and temperature on percutaneous penetration. This model can be used as a tool for rapid determination of initial estimates of skin permeability.}, number={3}, journal={CUTANEOUS AND OCULAR TOXICOLOGY}, author={Keshwani, DR and Jones, DD and Brand, RM}, year={2005}, pages={149–163} }