Changes In Dynamic Properties Research Articles

Experimental Study on the Photothermal Properties of Thermochromic Glass

Reducing energy consumption in buildings is critical to reducing CO2 emissions and mitigating global warming. Studies have shown that heating and cooling loads account for more than 40% of building energy consumption, and thermochromic glass (TCG) with dynamically adjustable solar transmittance is an excellent way to reduce this load. Although a large number of studies have tested the spectral parameters of TCG in totally transparent and totally turbid states, the impact of dynamic changes in optical properties on the simulation accuracy of building energy consumption has been neglected. In this study, a method is proposed for a hydrogel-type TCG to dynamically test its spectral parameters based on spectrophotometry. The method uses a spectrophotometer and a PID heater to achieve the dynamic optical parameter testing of TCGs at different temperatures. In this paper, the transmission and reflection spectra of the two TCGs at 20~25 °C, 30~35 °C, 40 °C, 45 °C, 50 °C, and 55 °C were obtained, and the regression segmentation functions of visible transmittance and solar transmittance were established. The R2 of the function model is 0.99. In addition, the test results show that the thermochromic glass selected in this paper can selectively transmit different wavelengths of light, and its transmission mainly occurs in the visible and near-infrared wavelengths from 320 to 1420 nm, while the transmission rate of other wavelengths is very low. As the temperature increases, the visible, solar, and ultraviolet transmittances decrease at a similar rate. In addition, the higher the temperature acting on the thermochromic (TC) layer, the greater its haze.

Distinctive Photomechanical Shape Change of p‐Phenylenediacrylic Acid Dimethyl Ester Single Crystals Induced by a Spatially Heterogeneous Photoreaction

AbstractUnderstanding photoreaction dynamics in crystals is important for predicting the dynamic property changes accompanying these photoreactions. In this work, we investigate the photoreaction dynamics of p‐phenylenediacrylic acid dimethyl ester (p‐PDAMe) in single crystals that show reaction front propagation, in which the photoreaction proceeds heterogeneously from the edge to the center of the crystal. Moreover, we find that p‐PDAMe single crystals exhibit a distinctive crystal shape change from a parallelogram to a distorted shape resembling a fluttering flag, then to a rectangle as the photoreaction proceeds. Density functional theory calculations predict the crystal structure after the photoreaction, providing a reasonable explanation of the distinctive crystal shape change that results from the spatially heterogeneous photoreaction. These results prove that the spatially heterogeneous photoreaction dynamics have the ability to induce novel crystal shape changes beyond what would be expected based on the equilibrium reactant and product crystal shapes.

Distinctive Photomechanical Shape Change of p-Phenylenediacrylic Acid Dimethyl Ester Single Crystals Induced by a Spatially Heterogeneous Photoreaction.

Understanding photoreaction dynamics in crystals is important for predicting the dynamic property changes accompanying these photoreactions. In this work, we investigate the photoreaction dynamics of p-phenylenediacrylic acid dimethyl ester (p-PDAMe) in single crystals that show reaction front propagation, in which the photoreaction proceeds heterogeneously from the edge to the center of the crystal. Moreover, we find that p-PDAMe single crystals exhibit a distinctive crystal shape change from a parallelogram to a distorted shape resembling a fluttering flag, then to a rectangle as the photoreaction proceeds. Density functional theory calculations predict the crystal structure after the photoreaction, providing a reasonable explanation of the distinctive crystal shape change that results from the spatially heterogeneous photoreaction. These results prove that the spatially heterogeneous photoreaction dynamics have the ability to induce novel crystal shape changes beyond what would be expected based on the equilibrium reactant and product crystal shapes.

Dynamic changes in chemical components, volatile profile and antioxidant properties of Xanthoceras sorbifolium leaf tea during manufacturing process.

In order to elucidate the dynamic changes of quality characteristics in Xanthoceras sorbifolium leaf tea (XLT), this work investigated the chemical components, volatile profile, and antioxidant properties at key stages of fixation, shaping, and drying. The process of fixation and drying emerged as critical stages that affected the chemical components and taste of XLT. Total polyphenols, reducing sugars and chlorophyll were the differential compounds, which decreased by 29.1%, 63.3% and 69.5% during processing, respectively. Threonine, glycine, arginine, reducing sugar, caffeine, catechin (C), and epicatechin gallate (ECG) were primary taste characteristic compounds. A total of 95 volatile organic components (VOCs) and 24 key odorants with relative odor activity value (ROAV)>1.0 were identified in XLT, ethyl 2-methylbutanoate-D, dimethyl disulfide, and ethyl isobutyrate (ROAV=100) were the central contributors to volatiles profile. Moreover, tea manufacturing enhanced the antioxidant potency composite (APC) by 1.1%, primarily due to its high water extract content.

Dynamic changes in interfacial and emulsifying properties of soy protein during fibrillation

The fibrillation process endows food proteins with exceptional techno-functional properties; however, these properties can be unstable owing to alterations in the structure and composition of a fibril system during fibrillation. This study comprehensively evaluated the interfacial and emulsification properties of the soy protein fibril system during the 24-h incubation under acid heating conditions (pH 2.0, 85 °C). Thioflavin T fluorescence and sodium dodecyl sulfate–polyacrylamide gel electrophoresis confirmed that the formation of soy protein nanofibrils (SPNFs) involved hydrolysis and self-assembly processes, ultimately transforming SPNFs into mature fibrils with a contour length of 276.7 nm and a β-sheet-rich structure after 18 h. Protein fragments formed during the initial stage (0–4 h) increased the diffusion rate of the fibril system to the oil–water interface. Prolonged incubation enhanced both the penetration and rearrangement of the fibril system accompanied by significant increases in the dynamic dilatational elastic and surface dilatational moduli. The fibril component was separated by ultrafiltration centrifugation and was proved crucial for maintaining high interfacial stability. Mature fibrils (18–24 h) were robustly adsorbed at the oil–water interface, forming a cream layer reinforced with hydrogen bonds, which significantly enhanced the emulsion stability. These findings elucidate the structural and interfacial property transformations of soy protein during fibrillation and provide a theoretical foundation for its strategic application in food processing.

Effect of sub‐coercive degradation on the local piezoelectric properties in lead zirconate titanate ceramics

AbstractLead zirconate titanate (PZT) is a widely recognized piezoelectric ceramic exhibiting excellent dielectric and ferroelectric properties over a wide range of temperature and frequency, making it desirable for applications such as capacitors, piezoelectric transducers, and actuators. Being subjected to repeated electrical loading in various applications, a progressive decrease in the functionality can happen, leading to device failure over time. Therefore, understanding degradation phenomena in all aspects is of importance to expand the lifespan of electronic devices. Despite of many studies focusing on the macroscopic properties of ferroelectrics related to degradation, such as switchable polarization, little is known about the change on local ferroelectric and piezoelectric properties and the domain structure induced by degradation. This paper reports the effect of sub‐coercive electrical cycling on local static and dynamic piezoelectric properties for PZT ceramic using piezoresponse force microscopy (PFM). The piezoelectric properties are probed along the three sample directions (x, y, z) to gain comprehensive insights into the local domain orientation throughout the bulk PZT sample which is then compared with microscopically measured piezoelectric coefficients. The PFM results are analyzed with respect to changes in domain orientation (depolarization) as well as to reduction on piezoelectric material response (degradation) to identify the origin of the degradation behavior. Our results directly show a strong depolarization effect in the direction of the applied electric field because of sub‐coercive cycling although it leads to small or even no degradation in directions perpendicular to the applied electric field. However, the latter is associated with a notable change in dynamic polarization switching properties which are strongly tied to the local domain structure. Our study shows that the origin of the degradation can be identified by analyzing the statistical change of local piezoelectric properties.

Quantification of soil nutrient stocks and stoichiometric ratios in Eucalyptus pellita biomass plantation chronosequence in Papua New Guinea

Eucalyptus pellita biomass tree plantations have been widely established in the native grasslands of Markham Valley in Papua New Guinea for bioenergy production and carbon capture. However, the impacts of converting grasslands to energy plantations, and the ensuing soil transformations across the plantation chronosequence, remain largely unexplored. Such land use transitions are associated with depletion of C sinks, increased C emissions, and potential implications for climate change. This study aimed to evaluate dynamic changes in key soil physico-chemical properties, as well as nutrient stocks of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP), alongwith their stoichiometric ratios. A chronosequence of E. pellita plantations aged 2-, 4-, 7- and 10-years along with native grassland sites, was examined across two sampling seasons (January and June). The results indicated significant (p < 0.05) impacts of tree stand age on SOC and TP concentration and stocks, while TN remained unaffected. Soil NH4+-N concentration declined with the plantation age, contrasting with relatively steady NO3–-N levels across the chronosequence. SOC and TP stocks within the top 45 cm of soil depleted at rates of 0.19 Mg (Mega Gram) ha-1y-1 and 0.011 Mg ha−1 y-1, respectively. The broader stoichiometric ratio of C:N (> 25:1) observed in soils of 4- and 7-year-old plantations suggest potential nitrogen immobilization and mineral N deficiency to tree nutrition. Conversely, the C:P ratios across the chronosequence were < 200, favoring the net mineralization of organic P compounds. Overall, afforestation of grasslands with E. pellita for biomass production does not appear ecologically beneficial in the short-term (<10 years), when considering only the belowground SOC sequestration potential.

Changes in starch properties during malting and their correlations with the malting quality of multiple barley cultivars

AbstractBackground and ObjectiveThere is still a lack of information about detailed dynamic changes in starch properties during malting among multiple barley varieties and correlations of starch properties with malting qualities. In this work, compositional, physicochemical, morphological, and structural properties of starches from four barley varieties at six time points across the malting process were first investigated to better understand the starch modification of barley malting. Furthermore, a total of 30 barley varieties were used to investigate the relationship between malting qualities and starch properties. The results provide a reference for breeding high‐malting quality barley based on starch properties.FindingsSignificant decreases in starch contents, paste viscosities, relative crystallinity, as well as the ratio of 1045/1022 cm−1 of starch, were exhibited, while comparatively small changes were found in the thermal parameters during malting. Amylose and amylopectin polymers were both hydrolyzed in malting. After malting, pits and holes were discovered on the surface of some starch granules. Four parameters of peak viscosity (PV), breakdown, peak time (PeT), and pasting temperature (PT) had significant correlations with diastatic power (DP), while the above four indicators together with amylose content, total starch content, onset temperature, peak temperature, and swelling power had significant correlations with malt extract (ME).ConclusionsThe trend of changes in starch properties among all four genotypes was similar. However, the variety with better malting quality showed a greater degree of measurements in some starch characters. Starch properties are mainly related to the two malting quality indicators of DP and ME.Significance and NoveltyPV, breakdown, PeT, and PT had significant correlations with malting qualities.

Evaluation of in vitro simulated digestion and fermentation characteristics of the crude exopolysaccharide from Levilactobacillus brevis M-14.

The present study employed an in vitro static digestion model to simulate the saliva-gastrointestinal digestion and fecal fermentation of exopolysaccharides (EPSs) extracted from Levilactobacillus brevis M-14, aiming to understand the dynamic changes in physicochemical properties, biological potential of EPS, as well as their impact on the human enteric microorganism. EPS was mainly composed of polysaccharides. The molecular weight (Mw) showed that EPS comprised two parts with a high Mw and a low Mw fraction of 42.81 × 104 and 1.23 × 104 Da, respectively. EPSs mainly consisted of mannose, rhamnose, galacturonic acid, glucose, and galactose in a molar ratio of 0.42∶0.13∶0.21∶0.13∶0.11. In the simulated digestion process, EPS was relatively stable. Furthermore, simulated digestion increased the antioxidant and hypoglycemic capacities of EPS. During the fermentation stage, the total carbohydrate contents of EPS decreased by 20.19%. The Mw of the two components of EPS decreased by 16.37% and 61.67%, respectively, and accompanied by the production of free monosaccharides. EPS had the potential to modulate the composition of gut microbiota, increasing the relative abundance of Enterococcus and Parabacteroides, while decreasing the relative abundance of Bacteroides. The pH decreased and total short-chain fatty acids contents increased, especially acetic acid and propionic acid. This research provided valuable insights into the potential application of EPS as a prebiotic agent.

Photomodulation of Charge Transfer through Excited‐State Processes: Directing Donor‐Acceptor Binding Dynamics

AbstractModulating charge transfer (CT) interactions between donor and acceptor molecules may give rise to unique dynamic changes in physicochemical properties, exhibiting great importance in supramolecular chemistry and materials science. In this work, we demonstrate the first instance of reversible photomodulation of donor‐acceptor (D−A) CT interaction in the solid state. Pyridinium‐based chromophore featuring π‐conjugated D−A structures can not only function as a good electron acceptor to undergo photoinduced electron transfer (ET) or engage in intermolecular CT interaction, but also exhibit unique dual emission depending on the excitation wavelengths. The rotatable C−C single bonds within D−A pairs enhance the tunability of molecular structure. Through the synergy of a photoinduced ET and an excited‐state conformational change, the intermolecular CT interaction can be switched on and off by alternate light irradiation to enable reversibly modulation of the affinity between donor and acceptor molecules, accompanied by visual color switching and fluorescence on‐off as feedback signals.

Dynamic changes in microbial communities and volatile compounds in kombucha fermentation using Flos sophorae and Elm fruits, compared to black and green tea

The dynamic changes in physicochemical properties, microbial communities, and volatile compounds in kombucha made from Flos sophorae (FLSK) and Elm fruit (EFK) were compared to those of black tea (BTK) and green tea (GTK) over a 12-day fermentation period. The results revealed that overall flavonoid and polyphenol content, as well as antioxidant activity, increased initially and then decreased, accompanied by a steady reduction in pH within the fermentation broths investigated. Notably, the GTK exhibited stronger antioxidant activity than the other fermentation broths. Furthermore, 16S rRNA gene sequencing revealed that Komagataeibacter rhaeticus, Komagataeibacter saccharivorans, and Acidovorax wautersii were the dominating microbial species in the fermentation broths under this study. Komagataeibacter rhaeticus initially reduced and then increased throughout the FLSK fermentation, whereas Komagataeibacter saccharivorans increased from day 0 to day 6, and remain stable by day 12 during the EFK fermentation. Comparative analysis revealed that Komagataeibacter rhaeticus was more abundant in the FLSK and GTK than in the EFK and BTK, whereas Komagataeibacter saccharivorans showed a higher abundance in the EFK relative to the other fermentation broths. Gas chromatography-mass spectrometry identified acetic acid, linalool, ethanol, and ethyl acetate as the major volatile chemicals that rose significantly in fermentation mixtures of the examined substrates. The FLSK had a much higher linalool concentration than the other fermentation broths, although the EFK and GTK had higher ethanol content. Correlation study found that Komagataeibacter rhaeticus was negatively related with alcohol compounds, but Komagataeibacter saccharivorans was positively associated with a diverse spectrum of acids, alcohols, and esters. The study found changes in bioactive chemicals as well as interactions between bacterial populations and volatile compounds throughout fermentation in the substrates investigated.

Analysis on temperature vacuum swing adsorption from wet flue gas carbon capture by using solid amine adsorbent with co-adsorption equilibrium models

Adsorption carbon capture has attracted extensive attention due to its low regeneration heat consumption, eco-friendly impacts and simplicity. However, there is a lack of comprehensive analysis of its energy consumption, economy and environment impact of adsorption carbon capture. This study aims to investigate the working performance using temperature vacuum swing adsorption (TVSA) from wet flue gas carbon capture utilizing co-adsorption equilibrium models for metal–organic framework (MOF) based amine materials. TVSA model is then carried out in terms of the continuous operational state, the dynamic changes in physical properties inside the bed, and the differences in properties at different positions within the bed layer. It is found that they often cannot simultaneously meet high CO2 recovery rates, productivity, and equivalent work. The analysis reveals that the optimal conditions, namely an adsorption temperature of 318 K and a CO2 component of 0.02 kmol during desorption, collectively result in reduced equivalent work and heightened productivity. The maximum productivity could reach 46.35 kg·m−3·h−1 for 5.6 v% water content and 308 K adsorption temperature. It is demonstrated that temperature vacuum swing adsorption for wet flue gas carbon capture using MOF based amine adsorbent is quite promising in terms of energy consumption and CO2 productivity in the future.

The dynamic changes and correlations between biochemical properties, flavor and microbial community during fermentation of asparagus by-products

Asparagus by-products are the promising resource that urgently need to be re-valorized. This study investigated the dynamic changes in physicochemical properties, organic acids, free amino acids, volatile flavor compounds, microbial succession, and their correlations during 7-day spontaneous fermentation of asparagus by-products. Dominant organic acids (lactic acid and acetic acid) and free amino acids (Ser, Glu, and Ala) increased with fermentation time, with lactic acid reaching 7.73 ± 0.05 mg/mL and Ser increasing 56-fold after 7 days. A total of 58 volatile flavor compounds were identified using headspace solid-phase microextraction-gas chromatography–mass spectrometry (HS-SPEM/GC–MS), with esters, alcohols and acids as the main volatile flavor compounds. Fourteen volatile flavor compounds had odor activity value >1. High-throughput sequencing showed Firmicutes and Proteobacteria as the main bacterial phyla, dominated by lactic acid bacteria (Levilactobacillus, Lactiplantibacillus, Weissella). Correlation analysis revealed that five bacterial genera (Levilactobacillus, Lactiplantibacillus, Enterobacter, Pediococcus and Acetobacter) were highly correlated with organic acids, free amino acids, and volatile flavor compounds, indicating their pivotal role in forming the characteristic flavor of fermented asparagus by-products (FAPS). This study provides new insights into the flavor and microbial profile of FAPS, offering a strategy for value-added processing and industrial production.

The dynamic changes in physicochemical properties, functionalities, and gel properties of the starch-konjac gum mixture during the melting process: Based on three typical melting temperatures of DSC

The present study focuses on investigating the effect of typical melting temperatures (To, Tp, and Tc from DSC) on the dynamic changes of physicochemical properties, functionalities, and gel properties of starch-konjac gum mixture (PS/KGM). The typical melting treatments (HTo, HTp, and HTc) significantly enhanced the PS/KGM synergism, as indicated by the increased thermal stability, and the improved pasting and gel properties. The work suggested that the typical melting effectively stabilized the aqueous mixture system of PS/KGM, showing no phase separation in the water phase system, even after storage for 12 h. The PLM and SEM show that melting at HTo, HTp, and HTc causes partial melting with the loss of birefringence of starch granules, and the granules conglomerate into large clusters with rough surfaces, surrounded by smaller matrices. DSC demonstrated that typical melting significantly raised the To of composite to approximately 77 from 59.10 °C for native. RVA suggested that the melting significantly increased the FV of PS/KGM from 3363 to approximately 8000 mPa s, while the BD decreased from 5009 to approximately 400 mPa·s. Especially in which there is no BD recorded when melted by HTp and HT. The PS/KGM melted by HTo and HTp had more acidic, salty, and shear stability during the thermal process with improved gel texture and freeze-thaw stability than HTc. Partial melting of starch and chain rearrangement is critical for enhancing PS/KGM synergism. As RC% and DM% controlling at approximately 30–35% are the most effective for promoting PS/KGM interaction (HTp > HTo > HTc).

In vitro fecal fermentation characteristics and dynamic changes in physicochemical and structural properties of oat β-glucan

Oat β-glucan (OG) is a common food in many diets, but the relationship between the structural changes of dietary fibre and the dynamic shifts in gut microbiota composition remains unclear. In this study, the dynamic variations of physicochemical and structural characteristics of OG at different fermentation stages were studied using an in vitro porcine colonic digestion model. lMeanwhile, the correlation between the molecular structure changes of OG and its regulation of gut microorganisms during fermentation was studied. The molecular weight of OG decreased with the prolongation of fermentation time due to the decomposition of the glucoside bond by gut microorganisms. Methylation analysis showed that the sugar residues in OG mainly included T-Glcp, 3-Glcp and 4-Glcp, while the proportions of 3-Glcp and 4-Glcp did not change significantly during the process of fermentation, demonstrating that gut microorganisms could equally decompose β-(1, 3) and β-(1, 4) glucoside bonds. During the fermentation process, OG inhibited the growth of harmful bacteria while promoting the growth of beneficial bacteria, especially Lactobacillus. Compared with gum arabic, hawthorn pectin, arabinoxylan, guar gum and dendrobium officinale polysaccharide, OG showed the fastest fermentation rate and highest Lactobacillus abundance. This study's results offer a scientific foundation for enhancing the conversion of oat β-glucan (OG) into prebiotics within the functional food industry. Additionally, they provide valuable insights into the reciprocal regulation between other structural polysaccharides and gut microorganisms.

Transcriptomic Analysis Reveals Dynamic Changes in Glutathione and Ascorbic Acid Content in Mango Pulp across Growth and Development Stages

Mango (Mangifera indica) is a highly valuable horticultural crop known for its quality and productivity. This study investigates the dynamic changes in physicochemical properties and glutathione and ascorbic acid metabolic pathways in mango pulp across various growth and development stages over two consecutive years (2021–2022 and 2022–2023) by transcriptomic analysis. Overall, the results demonstrate that during different ripening periods, the pulp shows increased levels of total soluble solids, relative conductivity, glutathione, and enzymes, while titratable acidity, malondialdehyde, reactive oxygen species, and ascorbic acid contents decreased. Moreover, transcriptomic analysis identified key differentially expressed genes from the glutathione and ascorbic acid metabolic pathways and validated them with qRT-PCR. In different comparisons, a total of 1776, 2513, and 828 DEGs were identified in 30 vs. 60, 30 vs. 90, and 60 vs. 90 days after flowering, respectively. Among them, seven DEGs were primarily enriched in relevant pathways, which included ascorbate peroxidase, ascorbate oxidase, glutathione peroxidase, gamma-glutamyl transferase, glutathione transferases, and glucose-6-phosphate dehydrogenase. The upregulation of these genes indicates that glutathione and AsA respond well to scavenging reactive oxygen species and maintain normal functioning in plants. This research sheds light on the molecular mechanisms of glutathione and ascorbic acid dynamic changes in mango pulp, providing valuable insights into the regulation of antioxidant and metabolic pathways during fruit growth and development.

Novel insights into the mechanism of dynamic changes in microstructure and physicochemical properties of corn straw pretreated by ball milling and feasibility analysis of anaerobic digestion

In this study, the effects of Ball milling (BM) pretreatment (0–240 min) on the microstructure, physicochemical properties and subsequent methanogenesis performance of corn straw (CS) were explored, and the feasibility analysis was carried out. The results showed that BM pretreatment destroyed the dense structure of the CS, and the particle size was significantly reduced (D50: 13.85 μm), transforming it into a cell-scale granular form. The number of mesopores increased, the pore volume (PV) (0.032 cm3/g) and specific surface area (SSA) (4.738 m2/g) considerably increased, and the water-absorbent property was improved. The crystalline order of cellulose was disrupted and the crystallinity (CrI) (8.61 %) and crystal size (CrS) (3.37) were remarkably reduced. The cross-links between lignocelluloses were broken, and the relative content and functional groups did not alter obviously. The bulk density (BD), repose angle (RA) and slip angle (SA) dramatically increased. As a result, CS was more readily accessible, attached and utilized by microorganisms and enzymes, causing the hydrolysis and acidification of AD to be greatly facilitated. Compared with the untreated group, the cumulative methane production (CMP) increased by 35.83 %–101.97 %, and the lag phase time (λ) was shortened by 33.04 %–71.17 %. The results of redundancy analysis, Pearson analysis and Mantel test showed that BM pretreatment affects the process of AD by changing the physicochemical factors of CS. The normalization analysis showed that particle size (D90) and BD can be used as direct indicators to evaluate the performance of AD and predict the threshold of biodegradation of CS. Energy analysis and energy conversion assessment showed that BM is a green and efficient AD pretreatment strategy. This result provides a theoretical basis for the industrial application of BM pretreatment towards more energy-efficient and sustainable development.

Dynamic Changes in Physicochemical Properties and Microbial Community in Three Types of Recycled Manure Solids for Dairy Heifers

Recycled manure solids (RMSs) are widely utilised as beddings due to their economic and environmentally friendly features. Internal change in RMSs plays a vital role in the stable operation and management of beddings. However, the internal microenvironment of various manure beddings has not been fully reported. Therefore, we evaluated the physicochemical properties, internal gases and changes in the microbial community of the in situ fermentation beds, which were prefermented by cow manure with sawdust (FSD), straw (FST) and sawdust–straw mixture (FM), at a farm in Jiangsu, China, from June to September 2022. The results indicated that the FSD and FM beds were more capable of degrading organic matter (OM), accumulating total nitrogen and processing a more stable pH environment. FSD bed promoted the conversion of nitrate–nitrogen and ammonium–nitrogen (NH4+-N). Different treatments and times had significant effects on bacterial and fungal communities. FSD enriched Chloroflexi, and FST enriched Actinobacteriota in the early stage, while FM enriched Proteobacteria in the late stage. Bacterial communities were more sensitive to NH4+-N and OM, while fungal communities were more sensitive to temperature and pH. FSD had potential advantages concerning N conversion and C emission reduction. The results of the study revealed the microenvironmental dynamics during bedding use, providing a theoretical basis for the use of a compost bedding system for managing recycled dairy manure.

Dynamic changes in the aggregation-depolymerization behavior of Ovomucin-Complex and its binding to urease during in vitro simulated gastric digestion

Ovomucin-Complex extracted from egg white is expected to have a barrier function similar to gastric mucin. In this study, the dynamic changes in structure, rheological properties and binding ability of Ovomucin-Complex during in vitro simulated gastric digestion were investigated. The results from HPLC and CLSM showed that extremely acidic pH (pH = 2.0) promoted Ovomucin-Complex to form aggregation. Acid-induced aggregation may hinder its binding to pepsin, thus rendering Ovomucin-Complex resistant to pepsin. Consequently, most of the polymer structure and weak gel properties of Ovomucin-Complex retained after simulated gastric digestion as verified by HPLC, CLSM and rheological measurement, although there was a small breakdown of the glycosidic bond as confirmed by the increased content of reducing sugar. The significantly reduced hydrophobic interactions of Ovomucin-Complex were observed under extremely acidic conditions and simulated gastric digestion compared with the native. Noticeably, the undigested Ovomucin-Complex after simulated gastric digestion showed a higher affinity (KD = 5.0 ± 3.2 nm) for urease - the key surface antigen of Helicobacter pylori. The interaction mechanism between Ovomucin-Complex and urease during gastric digestion deserves further studies. This finding provides a new insight to develop an artificial physical mucus barrier to reduce Helicobacter pylori infection.

Abstract 4388: Tumor-associated RhoA mutants interact with effectors in both GDP- and GTP-bound states

Abstract RhoA is the founding member of the Ras-homology (Rho) small GTPase family and is a master regulator for multiple cell functions. Recurrent RhoA mutations have been identified in several human cancers, particularly in leukemia/lymphoma and gastric cancer. Intriguingly, both gain-of-function and loss-of-function mutations of RhoA are present, suggesting that RhoA GTPase may have a more sophisticated role in cancer and requires more rigorous investigations. Here, we have focused on two of the gain-of-function RhoA mutations identified in Adult T cell Leukemia/lymphoma (ATLL) at residue A161 (A161P and A161V) and aim to reveal the underlying mechanistic basis for their function by biochemical and structural analyses. We found that in contrast to conventional gain-of-function RhoA mutants such as RhoAG14V and RhoAQ63L which affect the GTP-hydrolysis activity, RhoAA161P and RhoAA161Vare both fast-cycling with drastically increased nucleotide dissociation and association rates, but only slightly reduced GTP-hydrolysis activity. We solved the crystal structures of GDP-bound RhoAA161P and RhoAA161V and saw that while RhoAA161P displays impaired solvent-mediated interactions to the bound nucleotide, RhoAA161V has a more exposed nucleotide binding pocket compared to RhoAWT and RhoAA161P. Interestingly, RhoAA161P and RhoAA161Vcan interact with effector targets in the GDP-bound states. Further 1H-15N HSQC NMR study provides evidence of the active population in GDP-bound RhoAA161V. Molecule dynamics (MD) simulations show that the dynamic properties of RhoA switch regions are affected differently by the two mutations. Thus, RhoAA161V and RhoAA161P are fast-cycling mutants with distinct mechanisms, and both likely endow their GDP-bound state towards an active conformation. These findings provide a better understanding of the oncogenic role of RhoA mutations in cancer and shine light on how changes in RhoA protein dynamic properties caused by mutations may affect its function. Citation Format: Yuan Lin, Theresa A. Ramelot, Simge Senyuz, Attila Gursoy, Hyunbum Jang, Ruth Nussinov, Ozlem Keskin, Yi Zheng. Tumor-associated RhoA mutants interact with effectors in both GDP- and GTP-bound states [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4388.