Effect of different drying methods on the amino acids,α-dicarbonyls and volatile compounds of rape bee pollen

The significant demand for high quality food has motivated us to adopt appropriate processing methods to improve the food nutritional quality and flavors.In this study,the effects of five drying methods,namely,pulsed vacuum drying(PVD),freeze drying(FD),infrared drying(IRD),hot-air drying(HAD)and sun drying(SD)on free amino acids(FAAs),α-dicarbonyl compounds(α-DCs)and volatile compounds(VOCs)in rape bee pollen(RBP)were determined.The results showed that FD significantly released the essential amino acids(EAAs)compared with fresh samples while SD caused the highest loss.Glucosone was the dominantα-DCs in RBP and the highest loss was observed after PVD.Aldehydes were the dominant volatiles of RBP and SD samples contained more new volatile substances(especially aldehydes)than the other four drying methods.Comprehensively,FD and PVD would be potential methods to effectively reduce the quality deterioration of RBP in the drying process.

Regulating^(*)COOH intermediate via amino alkylation engineering for exceptionally effective photocatalytic CO_(2) reduction

Photocatalytic reduction of CO_(2) into fuel represents a promising approach for achieving carbon neutrality,while realizing high selectivity in this process is challenging due to uncontrollable reaction intermediate and retarded desorption of target products.Engineering the interface microenvironment of catalysts has been proposed as a strategy to exert a significant influence on reaction outcomes,yet it remains a significant challenge.In this study,amino alkylation was successfully integrated into the melem unit of polymeric carbon nitrides(PCN),which could efficiently drive the photocatalytic CO_(2) reduction.Experimental characterization and theoretical calculations revealed that the introduction of amino alkylation lowers the energy barrier for CO_(2) reduction into^(*)COOH intermediate,transforming the adsorption of^(*)COOH intermediate from the endothermic to an exothermic process.Notably,the as-prepared materials demonstrated outstanding performance in photocatalytic CO_(2) reduction,yielding CO_(2)at a rate of 152.8μmol h^(-1) with a high selectivity of 95.4%and a quantum efficiency of 6.6%.

Biochemistry and transcriptome analysis reveal condensed tannins alleviate liver injury induced by regulating cholesterol metabolism pathway

Free cholesterol has been considered to be a critical risk factor of nonalcoholic fatty liver disease(NAFLD).It remains unknown whether dietary intake of condensed tannins(CTs)have distinguishable effects to alleviate liver damage caused by a high cholesterol diet.Male C57BL/6 mice were fed a high cholesterol diet for 6 weeks,and given CTs treatment at a dosage of 200 mg/(kg·day)at the same time.The results indicated that compared with mice fed a normal diet,a high cholesterol diet group resulted in significant weight loss,dysregulation of lipid metabolism in blood and liver,and oxidative stress in the liver,but CTs treatment dramatically reversed these negative effects.Hematoxylin and eosin(H&E)staining and frozen section observation manifested that CTs treatment could effectively reduce the deposition of liver cholesterol and tissue necrosis caused by high cholesterol intake.CTs alleviated liver injury mainly by regulating the expression of related genes in cholesterol metabolism pathway and AMPK phosphorylation.Our results confirmed that CTs have remarkable cholesterol lowering and anti-liver injury effects in vivo.

Inhibitory effect of procyanidin B2 and tannin acid on cholesterol esterase and their synergistic effect with orlistat

This study was aimed to analyze the effect of procyanidin B2(PC)and tannin acid(TA)on the activities of cholesterol esterase(CEase)and the inhibitory mechanisms of enzymatic activity.The interaction mechanisms were investigated by enzymatic kinetics,multi-spectroscopy methods,thermodynamics analysis,molecular docking,and dynamic simulations.PC and TA could bind with CEase and inhibit the activity of enzyme in a mixed-competitive manner and non-competitive manner,which was verified by molecular docking simulations and dynamics simulations.Also,PC and TA showed the synergistic inhibition with orlistat.Fluorescence,UVvis and the thermodynamic analysis revealed that the complexes were formed from CEase and inhibitors by noncovalent interaction.As revealed by the circular dichroism results,both PC and TA decreased enzymatic activities by altering the conformations of CEase.The inhibition of PC and TA on CEase might be one mechanism for its cholesterol-lowering effect.

Enhanced photocatalytic performance of polymeric C_3N_4 doped with theobromine composed of an imidazole ring and a pyrimidine ring

Molecular doping has been proven to be an effective approach to adjusting the electronic structure of polymeric carbon nitride(PCN)and thus improving its optical properties and photocatalytic activity.Herein,theobromine,a compound composed of an imidazole ring and a pyrimidine ring,was first copolymerized with urea to prepared doped PCN.Experimental investigations and theoretical calculations indicate that,a narrowing in band gap and a positive shift in valence band positon happened to the theobromine doped PCN,owing to the synergistic effect between the pyrimidine ring and the imidazole ring in the theobromine molecule.Moreover,it is shown that the doping with theobromine at a suitable mass fraction makes the obtained sample exhibit decreased photoluminescent emission,enhanced photocurrent density,and reduced charge-transport resistance.Consequently,an enhancement in the photocatalytic activity for water oxidation is found for the sample,which oxygen evolution rate is 4.43 times higher than that of the undoped PCN.This work sheds light on the choice of the molecular dopants for PCN to improve its photocatalytic performance.

Experimental research and numerical simulation of the thermal performance of a tube-fin cold energy storage unit using water/modified expanded graphite as the phase change material

In this study,experimental and numerical investigations were conducted on a tube-fin heat-exchanger latent-heat cold energy storage unit.The fin side of the heat exchanger was filled with water as the energy storage medium,and modified expanded graphite(MEG)was employed to improve the thermal characteristics of water.The water contact angle of the expanded graphite decreased from 106.31°to 0°,and the hydrophilicity and the absorption rate of water significantly improved after the modification.Moreover,the experimental analyses of the charge/discharge process showed that the cooling capacity of the system filled with 90 wt.%water/MEG was 80.8%of that of pure water,whereas its cooling time was only 69.7%of that of pure water.The average power increased by 15.9%compared with that of water.The system filled with 90 wt.%water/MEG completed two energy charging and discharging cycles,whereas the system filled with water completed only 1.5 cycles within 15000 s.Furthermore,the effects of the flow rate and inlet temperature of the heat transfer fluid on the charging process were explored.Finally,a numerical model was built and validated to investigate the phase change behavior and the effect of the structure size on the performance of the system.The heat-exchanger fin spacing had no significant effect on the cold energy storage unit,whereas the vertical spacing of the tube pass had the highest effect.It can be concluded that the heat exchanger combined with high-thermal-conductivity water/MEG exhibits better energy storage capacity and working power,showing a wide application prospect in the field of cold energy storage.