Conformationally Restricted TRH Analogs: The Compatibility of a 6,5-Bicyclic Lactam-Based Mimetic with Binding to TRH-R

A pair of conformationally restricted TRH analogs have been synthesized. Both analogs have the central histidine of TRH replaced by a cyclohexylalanine unit, and both analogs contain a 6,5-bicyclic lactam ring fusing the proline peptide bond into a trans conformation. The analogs differ at the bridgehead stereocenter. The synthesis of the analogs utilized an anodic amide oxidation reaction to selectively functionalize a proline derivative and a titanium tetrachloride-initiated cyclization−rearrangement sequence to assemble the desired bicyclic ring skeleton. The analogs were compared with the unrestricted cyclohexyalanine-containing TRH analog (cyclohexyl-Ala2-TRH) in order to determine how the added lactam ring affected the affinity and the potency of the analog for TRH-R. Both the affinity and potency of the restricted analogs were found to be critically dependent on the bridgehead stereochemistry of the bicyclic ring. The analog having R stereochemistry at the bridgehead was 478 times more potent than the S isomer. In addition, the R isomer was found to be approximately 4.7 times more potent than its unrestricted counterpart. Similarly, the R isomer was found to have an affinity for TRH-R that was approximately 3.4 times the affinity of the unrestricted cyclohexyl-Ala2-TRH

Detection residual and threshold.

Detection residual and threshold.</p

Initial and desired data.

Initial and desired data.</p

Outputs with different controllers in sensor fault case.

(a) Velocity response under the nominal control and FTC, (b) Altitude response under the nominal control and FTC.</p

Fault estimation with the adaptive augmented observer.

(a) Estimation of fv, (b) Estimation of fh.</p

Isolation residuals and threshold.

(a) Second isolation residual J2 (m = 2, k = 1, s = 3), (b) Third isolation residual J3 (m = 3, k = 1, s = 4).</p

Simulation platform.

Simulation platform.</p

Disturbance estimation results via different observers.

(a) Estimation of d via the PI observer, (b) Estimation of d via the adaptive augmented observer.</p

Adsorption of CO₂ in Flue Gas by Polyethylenimine-Functionalized Adsorbents: Effects of the Support Morphology and Dispersion Mode of Amines

In recent years, the use of polyethylenimine (PEI)-functionalized adsorbents for CO2 capture from flue gas has gained significant attention due to its excellent adsorption capacity. However, the influences of suitable support materials and their morphology on the adsorption and desorption of CO2 have not been adequately explored. In this study, we investigate the impact of three nanostructures of SiO2 support, namely, silica nanospheres (SNPs), silica nanosheets (SNHs), and silica nanotubes (SNTs), on CO2 capture from ultralow emission flue gas, with special emphasis on key parameters such as the adsorption capacity, amine efficiency, kinetics, thermodynamics, cyclic stability, and optimal adsorption temperature to elucidate the crucial role of morphology. Experimental results demonstrated that SNHs facilitate the dispersion of PEI on their surface, thereby effectively utilizing the specific surface area and enhancing the dispersion of the active sites of PEI. This amine dispersion method successfully reduces the mass transfer resistance of CO2 during the adsorption process. Conversely, SNTs lead to PEI dispersion between support particles, resulting in increased diffusion resistance toward CO2 and consequently decreased adsorbent performance. For SNPs, the loading of PEI into the pores effectively prevented the degradation of the adsorption performance caused by PEI leaching during the cyclic use of the adsorbent. In addition, the larger pore volume of SNPs facilitated the loading of a greater number of PEI molecules. Notably, at 60 wt % PEI loading, SNPs exhibited a higher adsorption capacity (3.68 mmol/g), lower adsorption heat (51.91 kJ/mol), and reduced regeneration energy consumption (1.775 GJ/ton). This study sheds light on the role of the support morphology in adsorption processes and presents a novel strategy for designing solid amine adsorbents with favorable cycle stability, high CO2 capture performance, and efficient amine utilization

Overall control structure diagram of HFV.

Overall control structure diagram of HFV.</p