Designing biomass lignins for the biorefinery

4 páginas.- 3 figuras. 17 referencias.- Comunicación oral presentada en el 16th European Workshop on Lignocellulosics and Pulp (EWLP) Gothenburg, Sweden, June 28 – July 1, 2022As ever more component monomers are discovered, lignin can no longer be regarded as deriving from just the three canonical monolignols. Pathway intermediates and additional products of truncated biosynthesis are now established lignin monomers. The array of acylated monolignols continues to expand. Game-changing findings have demonstrated that phenolics from alternative pathways, including flavonoids and hydroxystilbenes, are also involved in lignification, expanding the traditional concept. Beyond the basic science intrigue, these findings propound exciting new avenues for valorizing lignins, or for producing more readily extractable or depolymerizable lignins, in crop and bioenergy plants.We further acknowledge lots of colleagues and collaborators, and funding from the Swiss National Science Foundation (Synergia) grant # CRS115_180258, and the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-SC0018409).N

Optimal Trajectory Planning and Linear Velocity Feedback Control of a Flexible Piezoelectric Manipulator for Vibration Suppression

Trajectory planning is an effective feed-forward control technology for vibration suppression of flexible manipulators. However, the inherent drawback makes this strategy inefficient when dealing with modeling errors and disturbances. An optimal trajectory planning approach is proposed and applied to a flexible piezoelectric manipulator system in this paper, which is a combination of feed-forward trajectory planning method and feedback control of piezoelectric actuators. Specifically, the joint controller is responsible for the trajectory tracking and gross vibration suppression of the link during motion, while the active controller of actuators is expected to deal with the link vibrations after joint motion. In the procedure of trajectory planning, the joint angle of the link is expressed as a quintic polynomial function. And the sum of the link vibration energy is chosen as the objective function. Then, genetic algorithm is used to determine the optimal trajectory. The effectiveness of the proposed method is validated by simulation and experiments. Both the settling time and peak value of the link vibrations along the optimal trajectory reduce significantly, with the active control of the piezoelectric actuators

Experimental Identification and Vibration Control of A Piezoelectric Flexible Manipulator Using Optimal Multi-Poles Placement Control

This paper presents experimental identification and vibration suppression of a flexible manipulator with piezoelectric actuators and strain sensors using optimal multi-poles placement control. To precisely identify the system model, a reduced order transfer function with relocated zeros is proposed, and a first-order inertia element is added to the model. Comparisons show the identified model match closely with the experimental results both in the time and frequency domains, and a fit of 97.2% is achieved. Based on the identified model, a full-state multi-poles placement controller is designed, and the optimal locations of the closed loop poles are determined where the move distance of the closed loop poles is the shortest. The feasibility of the proposed controller is validated by simulations. Moreover, the controller is tested for different locations of the closed loop poles, and an excellent performance of the optimal locations of the closed loop poles is shown. Finally, the effectiveness of the proposed controller is demonstrated by experiments. Results show that the vibrations of the expected modes are significantly diminished. Accordingly, multi-mode vibrations of the manipulator are well attenuated

Design and Analysis of a Compliant End-Effector for Robotic Polishing Using Flexible Beams

The contact force between the polishing tool and the workpiece is crucial in determining the surface quality in robotic polishing. Different from rigid end-effectors, this paper presents a novel compliant end-effector (CEE) for robotic polishing using flexible beams. The flexibility of the CEE helps to suppress the excessive displacement caused by the inertia of the polishing robot and avoids damaging the polishing tool and workpiece surface. In addition, the contact force can also be precisely estimated via the measurement of the CEE’s displacement using a capacitive position sensor. The design, modeling and experimental validation of the CEE are presented. Firstly, the analytical model of the CEE is established using the stiffness matrix method. Subsequently, the analytical model is verified by finite element analysis. Further, a prototype is manufactured, and its characteristics and performance are experimentally tested. The equivalent stiffness is measured to be 0.335 N/μm, and the first natural frequency along its working direction is 42.1 Hz. Finally, the contact force measurement using the CEE is compared with a force sensor. Under open-loop condition, the resolution of the contact force measurement is found to be 0.025 N, which makes the fine tuning of the contact force possible in robotic polishing

Anti-disturbance control of a piezo-driven micromanipulator with a non-minimum phase

In precision micromanipulation tasks, operation accuracy and anti-disturbance performance of micromanipulators are critical. This paper presents anti-disturbance control for a piezo-driven micromanipulator with a non-minimum phase. The micromanipulator is constructed by mounting a flexible manipulator on a parallel positioning stage. The micromotion and dynamic behavior of the micromanipulator are analyzed. Then, an anti-disturbance control strategy combining H-infinity feedback control and disturbance observer-based control for a non-minimum phase is designed to reduce disturbances and ensure control accuracy. Finally, the experimental measurement and control system is built. The observed phenomena show that sinusoidal disturbances are almost eliminated and the overshoot of step disturbances is significantly reduced. In addition, the time for suppressing the step disturbance is shortened from 0.9 to 0.3 s. Experiments verify the viability of the anti-disturbance control strategy

Experimental Identification and Vibration Control of A Piezoelectric Flexible Manipulator Using Optimal Multi-Poles Placement Control

This paper presents experimental identification and vibration suppression of a flexible manipulator with piezoelectric actuators and strain sensors using optimal multi-poles placement control. To precisely identify the system model, a reduced order transfer function with relocated zeros is proposed, and a first-order inertia element is added to the model. Comparisons show the identified model match closely with the experimental results both in the time and frequency domains, and a fit of 97.2% is achieved. Based on the identified model, a full-state multi-poles placement controller is designed, and the optimal locations of the closed loop poles are determined where the move distance of the closed loop poles is the shortest. The feasibility of the proposed controller is validated by simulations. Moreover, the controller is tested for different locations of the closed loop poles, and an excellent performance of the optimal locations of the closed loop poles is shown. Finally, the effectiveness of the proposed controller is demonstrated by experiments. Results show that the vibrations of the expected modes are significantly diminished. Accordingly, multi-mode vibrations of the manipulator are well attenuated

Experiment research on unfrozen water content and pore characteristic of cement improved soil under freeze-thaw cycle

Grouting with cementitious materials is a commonly-recognized measure to control the freezing and thawing deformation of artificial freezing strata. This study investigated the unfrozen water content of silty clay with different cement content under freeze-thaw condition, as well as the pore characteristics of the silty clay before and after freeze-thaw cycle based on nuclear magnetic resonance. It analyzed pore characteristics variation patterns of cement improved soil before and after freeze-thaw cycle and the micro-mechanism of freeze-thaw damage through scanning electron microscopy and mercury intrusion porosimetry. Results showed that: ①With the same water content, the increase of cement content would lead to the initial increase and subsequent decrease in the sensitivity to temperature of water molecule magnetization in the pores. ②When the cement content is between 0%~10% and at the same temperature during thawing process, the increase of cement content would lead to the initial decrease and subsequent increase of the unfrozen water content in the frozen soil. ③Compared with the silty clay without cement, cement improved silty clay shows little changes in its pores before and after the freeze-thaw cycle. The pore characteristics and microstructure of improved silty clay with cement content of 5% are less affected by freeze-thaw cycle. This research can provide references for the study of freeze-thaw resistance of improved soil and the stability control of strata frost heave and thaw settlement in artificial frozen engineering

Characterization and Elimination of Undesirable Protein Residues in Plant Cell Wall Materials for Enhancing Lignin Analysis by Solution-State Nuclear Magnetic Resonance Spectroscopy

12 páginas.-- 5 figuras.-- 5 tablas.-- 74 referenciasProtein polymers exist in every plant cell wall preparation, and they interfere with lignin characterization and quantification. Here, we report the structural characterization of the residual protein peaks in 2D NMR spectra in corn cob and kenaf samples and note that aromatic amino acids are ubiquitous and evident in spectra from various other plants and tissues. The aromatic correlations from amino acid residues were identified and assigned as phenylalanine and tyrosine. Phenylalanine's 3/5 correlation peak is superimposed on the peak from typical lignin p-hydroxyphenyl (H-unit) structures, causing an overestimation of the H units. Protein contamination also occurs when using cellulases to prepare enzyme lignins from virtually protein-free wood samples. We used a protease to remove the protein residues from the ball-milled cell walls, and we were able to reveal H-unit structures in lignins more clearly in the 2D NMR spectra, providing a better basis for their estimationThis work was supported by grants from the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DEFC02-07ER64494). We are grateful for Jane Marita for her various helpful discussions on this project. We also thank Steven Karlen for GC/MS experimental support and Kris Niemann (USDFRC) for assistance with nitrogen analysis.Peer reviewe

Characterization of protein amino acid residues and a monolignol conjugate in whole plant cell walls by solution-state 2D NMR and their interference with authentic p-hydroxyphenyl (H) unit estimation

Resumen de la comunicación presentada en el 255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water (New Orleans), LA 18-22, march 2018Protein polymers exist in every plant cell wall preparation, and they interfere with lignin characterization and quantification. The current solution-state 2D NMR technique for whole plant cell wall structural profiling provides detailed information regarding cell walls. However, certain components intrude on lignin structural analysis. Here we report the structural characterization of the residual protein peaks in 2D NMR spectra in corn cob and kenaf samples, and note that aromatic amino acids are ubiquitous and evident in spectra from various other plants and tissues. The aromatic correlations from amino acid residues were identified and assigned as phenylalanine and tyrosine. Phenylalanine’s 3/5 correlation peak is superimposed on the peak from typical lignin p-hydroxyphenyl (H-unit) structures, causing an overestimation of the H units. Similarly, protein residues in many species also result in incorrect values for lignin analyses by the Klason method. Protein contamination also occurs when using cellulases to prepare enzyme lignins from virtually protein-free wood samples. We used a protease to remove the protein residues from the ballmilled cell walls, and we were able to reveal H-unit structures in lignins more clearly in the 2D NMR spectra, providing a better basis for their estimation. We also recently characterized a new monolignol conjugate, ML-benzoate (BA), in the cell wall samples of leaf tissues from Canary Island date palm (Phoenix canariensis). These NMR correlations have not been observed from other plant families including commelinid monocotyledons, such as the Poaceae (grasses, e.g., maize, rice, brachypodium). The presence of lignin-bound benzoates BA in the palms (Arecaceae) is very distinguishable. However, benzoate’s 3/5 correlation peak is virtually superimposed on the peak from typical lignin p-hydroxyphenyl (H-unit) structures, also causing an overestimation of the H units.Protein polymers exist in every plant cell wall preparation, and they interfere with lignin characterization and quantification. The current solution-state 2D NMR technique for whole plant cell wall structural profiling provides detailed information regarding cell walls. However, certain components intrude on lignin structural analysis. Here we report the structural characterization of the residual protein peaks in 2D NMR spectra in corn cob and kenaf samples, and note that aromatic amino acids are ubiquitous and evident in spectra from various other plants and tissues. The aromatic correlations from amino acid residues were identified and assigned as phenylalanine and tyrosine. Phenylalanine’s 3/5 correlation peak is superimposed on the peak from typical lignin p-hydroxyphenyl (H-unit) structures, causing an overestimation of the H units. Similarly, protein residues in many species also result in incorrect values for lignin analyses by the Klason method. Protein contamination also occurs when using cellulases to prepare enzyme lignins from virtually protein-free wood samples. We used a protease to remove the protein residues from the ballmilled cell walls, and we were able to reveal H-unit structures in lignins more clearly in the 2D NMR spectra, providing a better basis for their estimation. We also recently characterized a new monolignol conjugate, ML-benzoate (BA), in the cell wall samples of leaf tissues from Canary Island date palm (Phoenix canariensis). These NMR correlations have not been observed from other plant families including commelinid monocotyledons, such as the Poaceae (grasses, e.g., maize, rice, brachypodium). The presence of lignin-bound benzoates BA in the palms (Arecaceae) is very distinguishable. However, benzoate’s 3/5 correlation peak is virtually superimposed on the peak from typical lignin p-hydroxyphenyl (H-unit) structures, also causing an overestimation of the H units.Peer reviewe