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1.
Food Chem ; 460(Pt 2): 140698, 2024 Jul 31.
Article in English | MEDLINE | ID: mdl-39098192

ABSTRACT

Resveratrol is a promising functional ingredient applied in food products. However, low bioavailability and poor water solubility, which can be improved by glycosylation, hinder its application. A uridine diphosphate-dependent glycosyltransferase (UGT) from Bacillus subtilis 168 (named UGTBS) presents potential application for resveratrol glycosylation; nonetheless, imprecise regioselectivity renders the synthesis of resveratrol-3-O-ß-D-glucoside (polydatin) difficult. Therefore, molecular evolution was applied to UGTBS. A triple mutant Y14I/I62G/M315W was developed for 3-OH glycosylation of resveratrol and polydatin accounted for 91% of the total product. Kinetic determination and molecular docking indicated that the enhancement of hydrogen bond interaction and altered conformation of the binding pocket increases the enzyme's affinity for the 3-OH group, stabilizing the enzyme-substrate intermediate and promoting polydatin formation. Furthermore, a fed-batch cascade reaction by periodic addition of resveratrol was conducted and nearly 20 mM polydatin was obtained. The mutant Y14I/I62G/M315W can be used for polydatin manufacture.

2.
Adv Healthc Mater ; : e2401787, 2024 Aug 05.
Article in English | MEDLINE | ID: mdl-39101321

ABSTRACT

Type I photodynamic therapy (PDT) generates reactive oxygen species (ROS) through oxygen-independent photoreactions, making it a promising method for treating hypoxic tumors. However, the superoxide anion (O2∙-) generated usually exhibits a low oxidation capacity, restricting the antitumor efficacy of PDT in clinical practice. Herein, a photoactivated self-assembled nanoreactor (1-NBS@CeO2) is designed through integration of type I PDT and cerium oxide (CeO2) nanozymes for inducing cascade-amplified oxidative stress in hypoxic tumors. The nanoreactor is constructed though co-assembly of an amphiphilic peptide (1-NBS) and CeO2, giving well-dispersed spherical nanoparticles with enhanced superoxide dismutase (SOD)-like and peroxidase (POD)-like activities. Following light irradiation, 1-NBS@CeO2 undergoes type I photoreactions to generated O2∙-, which is further catalyzed by the nanoreactors, ultimately forming hypertoxic hydroxyl radical (∙OH) through cascade-amplified reactions. The PDT treatment using 1-NBS@CeO2 results in elevation of intracellular ROS and depletion of GSH content in A375 cells, thereby inducing mitochondrial dysfunction and triggering apoptosis and ferroptosis of tumor cells. Importantly, intravenous administration of 1-NBS@CeO2 alongside light irradiation showcases enhances antitumor efficacy and satisfactory biocompatibility in vivo. Together, the self-assembled nanoreactor facilitates cascade-amplified photoreactions for achieving efficacious type I PDT, which holds great promise in developing therapeutic modules towards hypoxic tumors.

3.
Bioresour Technol ; : 131177, 2024 Aug 01.
Article in English | MEDLINE | ID: mdl-39097240

ABSTRACT

Biological degradation of PET plastic holds great potential for plastic recycling. However, the high costs associated with preparing free enzymes for degrading PET make it unfeasible for industrial applications. Hence, we developed various cell catalysts by surface-displaying PETase mutants and MHETase using autotransporters in E. coli and P. putida. The efficiency of surface display was enhanced through modifying the host, co-expressing molecular chaperones, and evoluting the autotransporter. In strain EC9F, PET degradation rate was boosted to 3.85 mM/d, 51-fold and 23-fold increase compared to free enzyme and initial strain ED1, respectively. The reusability of cell catalyst EC9F was demonstrated with over 38 % and 30 % of its initial activity retained after 22 cycles of BHET degradation and 3 cycles of PET degradation. The highest reported PET degradation rate of 4.95 mM/d was achieved by the dual-enzyme cascade catalytic system EC9F+EM2 + R, a mixture of cell catalyst EC9F and EM2 with surfactant rhamnolipid.

4.
bioRxiv ; 2024 Jul 26.
Article in English | MEDLINE | ID: mdl-39091865

ABSTRACT

INTRODUCTION: The amyloid cascade hypothesis predicts that amyloid-beta (Aß) aggregation drives tau tangle accumulation. We tested competing causal and non-causal hypotheses regarding the direction of causation between Aß40 and Aß42 and total Tau (t-Tau) plasma biomarkers. METHODS: Plasma Aß40, Aß42, t-Tau, and neurofilament light chain (NFL) were measured in 1,035 men (mean = 67.0 years) using Simoa immunoassays. Genetically informative twin modeling tested the direction of causation between Aßs and t-Tau. RESULTS: No clear evidence that Aß40 or Aß42 directly causes changes in t-Tau was observed; the alternative causal hypotheses also fit the data well. In contrast, exploratory analyses suggested a causal impact of the Aß biomarkers on NFL. Separately, reciprocal causation was observed between t-Tau and NFL. DISCUSSION: Plasma Aß40 or Aß42 do not appear to have a direct causal impact on t-Tau. In contrast, Aß aggregation may causally impact NFL in cognitively unimpaired men in their late 60s.

5.
Chemistry ; : e202402469, 2024 Aug 14.
Article in English | MEDLINE | ID: mdl-39140465

ABSTRACT

The past few decades have witnessed tremendous development within epoxides. Among the many known reactions involving epoxide, Meinwald rearrangements represent one of the most important and attractive approaches, which can transform epoxides into versatile carbonyl compounds. Given the high efficiency of this protocol, substantial efforts have been made by researchers by utilizing multiple catalyst systems. This review provides an overview of recent advances in the Meinwald rearrangement (from 2014 onward), along with detailed discussions on mechanistic insights. This review aims to highlight the importance and value of these methodologies, thereby promoting further investigation and application.

6.
Angew Chem Int Ed Engl ; : e202413753, 2024 Aug 13.
Article in English | MEDLINE | ID: mdl-39138131

ABSTRACT

Silacycles have exhibited significant potential for application in the fields of medicinal chemistry, agrochemistry, and materials science. Accordingly, the development of effective methods for synthesizing these compounds has attracted increasing attention. Here, we report an efficient Cu-catalyzed enantioselective hydrosilylation of arylmethylenecyclopropanes with hydrosilanes, that allows the rapid assembly of various enantioenriched carbon- and silicon-stereogenic silacyclopentanes in good yields with excellent enantioselectivities and diastereoselectivities under mild conditions. Further stereospecific transformation of the Si-H bond on the chiral silicon center expands the diversity of these C- and Si-stereogenic silacyclopentanes.

7.
Bioorg Chem ; 151: 107707, 2024 Aug 08.
Article in English | MEDLINE | ID: mdl-39128243

ABSTRACT

Isoprene chemoenzymatic cascades (ICCs) overcome the complexity of natural pathways by leveraging a streamlined two-enzyme cascade, facilitating efficient synthesis of C5-isoprene diphosphate precursors from readily available alcohol derivatives. Despite the documented promiscuity of enzymes in ICCs, exploration of their potential for accessing novel compounds remains limited, and existing methods require additional enzymes for generating longer-chain diphosphates. In this study, we present the utility of Streptococcus mutans undecaprenol kinase (SmUdpK) for the chemoenzymatic synthesis of diverse non-natural isoprenoids. Using a library of 50 synthetic alcohols, we demonstrate that SmUdpK's promiscuity extends to allylic chains as small as four carbons and benzylic alcohols with various substituents. Subsequently, SmUdpK is utilized in an ICC with isopentenyl phosphate kinase and aromatic prenyltransferase to generate multiple non-natural isoprenoids. This work provides evidence that, with proper optimization, SmUdpK can act as the first enzyme in these ICCs, enhancing access to both valuable and novel compounds.

8.
Article in English | MEDLINE | ID: mdl-39133226

ABSTRACT

PURPOSE: This review focuses on extensive macular atrophy with pseudodrusen-like appearance (EMAP), a recently described maculopathy presenting with pseudodrusen-like lesions and chorioretinal atrophy more pronounced in the vertical axis. METHODS: Narrative review of the literature published until May 2024. RESULTS: The early onset age of EMAP (50-55 years) and its distinctive natural history, which includes night blindness followed by severe vision loss, differentiate it from atrophic age-related macular degeneration (AMD). A clear pathogenesis has not been determined, but risk factors include female gender and complement system abnormalities (altered levels of C3 and CH50). Moreover, lifelong exposure to pesticides has been suggested as risk factor for direct neuronal degeneration involving rods and cones. In the early phase of the disease, reticular pseudodrusen-like lesions appear in the superior perifovea and tend to coalescence horizontally into a flat, continuous, reflective material localized between the retinal pigmented epithelium and Bruch's membrane. Over time, EMAP causes profound RPE and outer retinal atrophy in the macular area, with a recent classification reporting a 3-stages evolution pattern. Blue autofluorescence showed rapidly evolving atrophy with either hyperautofluorescent or isoautofluorescent borders. Significant similarities between the diffuse-trickling phenotype of geographic atrophy and EMAP have been reported. Macular neovascularization is a possible complication. CONCLUSION: EMAP is specific form of early-onset atrophic macular degeneration with rapid evolution and no treatment. Further studies are needed to assess the best management.

9.
Bioorg Chem ; 151: 107694, 2024 Aug 05.
Article in English | MEDLINE | ID: mdl-39151388

ABSTRACT

An unprecedented metal-free synthesis of fused quinoxaline 1,5-disubstituted-[1,4]-diazepine hybrids have been reported under mild conditions through a domino intermolecular SNAr followed by an internal nucleophile-triggered intramolecular SNAr pathway. Our strategy offers the flexibility for the introduction of a broad variety of functionalities at the N-1 position of fused diazepine moiety by using suitable diamine tails to design structurally diverse scaffolds. The DNA binding properties of representative quinoxaline diazepine hybrids were studied using UV-vis absorbance and EtBr displacement assay and were found to be governed by the functionalities at the N-1 position. Interestingly, compound 11f containing the N-1 benzyl substitution demonstrated significant DNA binding (KBH âˆ¼ 2.15 ± 0.25 × 104 M-1 and Ksv âˆ¼ 12.6 ± 1.41 × 103 M-1) accompanied by a bathochromic shift (Δλ âˆ¼ 5 nm). In silico studies indicated possible binding of diazepine hybrid 11f at the GC-rich major groove in the ct-DNA hexamer duplex and showed comparable binding energies to that of ethidium bromide. The antiproliferative activity of compounds was observed in the given order in different cell lines: (HeLa > HT29 > SKOV 3 > HCT116 > HEK293). Lead compound 11f demonstrated maximum cytotoxicity (IC50 value of 13.30 µM) in HeLa cell lines and also caused early apoptosis-mediated cell death in cancer cell lines. We envision that our work will offer newer methodologies for the construction of fused quinoxaline 1,5-disubstituted-[1,4]-diazepine class of molecules.

10.
Sci Total Environ ; : 175535, 2024 Aug 14.
Article in English | MEDLINE | ID: mdl-39151636

ABSTRACT

Cascade reservoirs construction can greatly alter flow regime and sediment transport of rivers, further affecting migration and transformation processes of biogenic elements. The Jinsha River (JSR) is the China's largest hydropower base and the main runoff, sediment suspension, and nutrient source areas of the Yangtze River. However, the distribution, transport, and retention patterns of biogenic elements in the JSR are still unclear under the influence of cascade reservoirs. Therefore, monthly concentration monitoring work was conducted from November 2021 to October 2023 for various forms of carbon (C), nitrogen (N), phosphorus (P), and silicon (Si). Results showed that the concentrations and fluxes of total phosphorus (TP) and particulate phosphorus (PP) exhibited continuous decreasing trends along the reservoirs cascade, whereas N exhibited contrasting trends. The concentrations of dissolved total carbon (DTC), dissolved inorganic carbon (DIC), and total silicon also showed decreasing trends from upstream to downstream, whereas their fluxes were primarily influenced by runoff and exhibited upward fluctuations. Compared with other biogenic elements, there was a more pronounced retention effect on TP and PP by reservoirs, with average retention rates of 8.29 % and 16.01 %, respectively. Longer hydraulic retention time (HRT) can retain more TP and PP. Meanwhile, the retention rates of DTC, DIC, and particulate silicon were positively correlated with HRT, while the retention rate of dissolved silicon (DSi) showed a positive correlation with reservoir age. Moreover, the higher ratios of dissolved inorganic nitrogen to dissolved inorganic phosphorus (DIP) and DSi to DIP have occurred, resulting in apparent P limitation, particularly during the non-flood season due to lower DIP concentration. Overall, cascade reservoirs construction exists great influences on the spatial allocation, fluxes transport, and biogeochemical cycles of biogenic elements, potentially affecting the stability of rivers ecosystem along the food chain network.

11.
Sci Rep ; 14(1): 18447, 2024 08 08.
Article in English | MEDLINE | ID: mdl-39117690

ABSTRACT

Disorders of gallbladder motility can lead to serious pathology. Bitter tastants acting upon bitter taste receptors (TAS2R family) have been proposed as a novel class of smooth muscle relaxants to combat excessive contraction in the airways and other organs. To explore whether this might also emerge as an option for gallbladder diseases, we here tested bitter tastants for relaxant properties and profiled Tas2r expression in the mouse gallbladder. In organ bath experiments, the bitter tastants denatonium, quinine, dextromethorphan, and noscapine, dose-dependently relaxed the pre-contracted gallbladder. Utilizing gene-deficient mouse strains, neither transient receptor potential family member 5 (TRPM5), nor the Tas2r143/Tas2r135/Tas2r126 gene cluster, nor tuft cells proved to be required for this relaxation, indicating direct action upon smooth muscle cells (SMC). Accordingly, denatonium, quinine and dextromethorphan increased intracellular calcium concentration preferentially in isolated gallbladder SMC and, again, this effect was independent of TRPM5. RT-PCR revealed transcripts of Tas2r108, Tas2r126, Tas2r135, Tas2r137, and Tas2r143, and analysis of gallbladders from mice lacking tuft cells revealed preferential expression of Tas2r108 and Tas2r137 in tuft cells. A TAS2R143-mCherry reporter mouse labeled tuft cells in the gallbladder epithelium. An in silico analysis of a scRNA sequencing data set revealed Tas2r expression in only few cells of different identity, and from in situ hybridization histochemistry, which did not label distinct cells. Our findings demonstrate profound tuft cell- and TRPM5-independent relaxing effects of bitter tastants on gallbladder smooth muscle, but do not support the concept that these effects are mediated by bitter receptors.


Subject(s)
Gallbladder , Muscle, Smooth , Receptors, G-Protein-Coupled , TRPM Cation Channels , Animals , Mice , Calcium/metabolism , Dextromethorphan/pharmacology , Gallbladder/metabolism , Mice, Inbred C57BL , Mice, Knockout , Muscle Relaxation/drug effects , Muscle, Smooth/metabolism , Myocytes, Smooth Muscle/metabolism , Myocytes, Smooth Muscle/drug effects , Noscapine/pharmacology , Quaternary Ammonium Compounds/pharmacology , Quinine/pharmacology , Receptors, G-Protein-Coupled/metabolism , Receptors, G-Protein-Coupled/genetics , Signal Transduction , Taste/physiology , TRPM Cation Channels/metabolism , TRPM Cation Channels/genetics , Tuft Cells/metabolism
12.
Sensors (Basel) ; 24(15)2024 Jul 23.
Article in English | MEDLINE | ID: mdl-39123809

ABSTRACT

We live in the era of large data analysis, where processing vast datasets has become essential for uncovering valuable insights across various domains of our lives. Machine learning (ML) algorithms offer powerful tools for processing and analyzing this abundance of information. However, the considerable time and computational resources needed for training ML models pose significant challenges, especially within cascade schemes, due to the iterative nature of training algorithms, the complexity of feature extraction and transformation processes, and the large sizes of the datasets involved. This paper proposes a modification to the existing ML-based cascade scheme for analyzing large biomedical datasets by incorporating principal component analysis (PCA) at each level of the cascade. We selected the number of principal components to replace the initial inputs so that it ensured 95% variance retention. Furthermore, we enhanced the training and application algorithms and demonstrated the effectiveness of the modified cascade scheme through comparative analysis, which showcased a significant reduction in training time while improving the generalization properties of the method and the accuracy of the large data analysis. The improved enhanced generalization properties of the scheme stemmed from the reduction in nonsignificant independent attributes in the dataset, which further enhanced its performance in intelligent large data analysis.

13.
Molecules ; 29(15)2024 Jul 26.
Article in English | MEDLINE | ID: mdl-39124910

ABSTRACT

A novel synthesis strategy to access 2-alkoxyquinoline derivatives via a palladium-driven cascade reaction is disclosed. Unlike classic methods based on the alkylation of 2-quinolones with alkyl halides, the present method benefits from the de novo assembly of the quinoline core starting from 1,3-butadiynamides. Palladium-catalyzed reaction cascades with N-(2-iodophenyl)-N-tosyl-1,3-butadiynamides and primary alcohols as external nucleophiles proceed under mild reaction conditions and selectively deliver a variety of differently functionalized 4-alkenyl 2-alkoxyquinolines in a single batch transformation.

14.
Angew Chem Int Ed Engl ; : e202411598, 2024 Aug 16.
Article in English | MEDLINE | ID: mdl-39150042

ABSTRACT

As a promising gene therapy strategy, controllable small molecule-mRNA covalent modification in tumor cells could be initiated by singlet oxygen (1O2) to complete the modification process. However, in vivo generation of 1O2 is usually dependent on excitation of external light, and the limited light penetration of tissues greatly interferes the development of deep tumor phototherapy. Here, we constructed a tumor-targeting nano-micelle for the spontaneous intracellular generation of 1O2 without the need for external light, and inducing a high level of covalent modification of mRNA in tumor cells. Luminal and Ce6 were chemically bonded to produce 1O2 by chemiluminescence resonance energy transfer (CRET) triggered by high levels of hydrogen peroxide (H2O2) in the tumor microenvironment. The sufficient 1O2 oxidized the loaded furan to highly reactive dicarbonyl moiety, which underwent cycloaddition reaction with adenine (A), cytosine (C) or guanine (G) on the mRNA for interfering with the tumor cell protein expression, thereby inhibiting tumor progression. In vitro and in vivo experiments demonstrated that this self-initiated gene therapy nano-micelle could induce covalent modification of mRNA by 1O2 without external light, and the process could be monitored in real time by fluorescence imaging, which provided an effective strategy for RNA-based tumor gene therapy.

15.
Front Endocrinol (Lausanne) ; 15: 1398436, 2024.
Article in English | MEDLINE | ID: mdl-39104820

ABSTRACT

Background: Multiple Endocrine Neoplasia type 1 (MEN1) is an autosomal dominant disorder marked by pathogenic variants in the MEN1 tumor suppressor gene, leading to tumors in the parathyroid glands, pancreas, and pituitary. The occurrence of ACTH-producing pancreatic neuroendocrine carcinoma is exceedingly rare in MEN1. Case presentation: This report details a Colombian family harboring a novel MEN1 variant identified through genetic screening initiated by the index case. Affected family members exhibited primary hyperparathyroidism (PHPT) symptoms from their 20s to 50s. Uniquely, the index case developed an ACTH-secreting pancreatic neuroendocrine carcinoma, a rarity in MEN1 syndromes. Proactive screening enabled the early detection of pituitary neuroendocrine tumors (PitNETs) as microadenomas in two carriers, with subsequent surgical or pharmacological intervention based on the clinical presentation. Conclusion: Our findings underscore the significance of cascade screening in facilitating the early diagnosis and individualized treatment of MEN1, contributing to better patient outcomes. Additionally, this study brings to light a novel presentation of ACTH-producing pancreatic neuroendocrine carcinoma within the MEN1 spectrum, expanding our understanding of the disease's manifestations.


Subject(s)
Adrenocorticotropic Hormone , Carcinoma, Neuroendocrine , Multiple Endocrine Neoplasia Type 1 , Pancreatic Neoplasms , Pedigree , Humans , Pancreatic Neoplasms/genetics , Pancreatic Neoplasms/diagnosis , Male , Carcinoma, Neuroendocrine/genetics , Carcinoma, Neuroendocrine/pathology , Colombia , Multiple Endocrine Neoplasia Type 1/genetics , Multiple Endocrine Neoplasia Type 1/complications , Female , Middle Aged , Follow-Up Studies , Adrenocorticotropic Hormone/blood , Adrenocorticotropic Hormone/metabolism , Adult , Proto-Oncogene Proteins/genetics
16.
Mol Cell ; 2024 Jul 31.
Article in English | MEDLINE | ID: mdl-39111310

ABSTRACT

Canonical prokaryotic type I CRISPR-Cas adaptive immune systems contain a multicomponent effector complex called Cascade, which degrades large stretches of DNA via Cas3 helicase-nuclease activity. Recently, a highly precise subtype I-F1 CRISPR-Cas system (HNH-Cascade) was found that lacks Cas3, the absence of which is compensated for by the insertion of an HNH endonuclease domain in the Cas8 Cascade component. Here, we describe the cryo-EM structure of Selenomonas sp. HNH-Cascade (SsCascade) in complex with target DNA and characterize its mechanism of action. The Cascade scaffold is complemented by the HNH domain, creating a ring-like structure in which the unwound target DNA is precisely cleaved. This structure visualizes a unique hybrid of two extensible biological systems-Cascade, an evolutionary platform for programmable DNA effectors, and an HNH nuclease, an adaptive domain with a spectrum of enzymatic activity.

17.
ISA Trans ; 2024 Jul 20.
Article in English | MEDLINE | ID: mdl-39112127

ABSTRACT

In contemporary scenario, electric power companies have observed upsurge in penetration level of tidal power plants (TPPs) in the traditional electric power system framework. However, the tidal turbines offer less frequency assistance due to their lesser rotor mass. Hence, TPPs may be collaborated with conventional units like diesel engine generator (DEG) to confirm system frequency stability in multi-area micro-grid system. The DEG comprises of primary and proportional integral derivative (PID) secondary frequency controls. However, in TPPs, to advance the system frequency regulation, deloading control approach is suggested and a cascade fuzzy fractional order PID-ID with derivative filter (CFFOPID-IDF) droop controller is suggested in place of the conventional non-cascade controller droop in the deloaded region. The suggested controller gains are fetched exploiting Salps swarm algorithm. For further enhancement of the dynamic responses, a precise high voltage direct current (AHVDC) link with the inertia emulation-based control (INEC) scheme is adopted, which allows the utilization of the gathered energy from the capacitance of the HVDC interface for frequency regulation. It provides better results compared to conventional AC tie line interface having less undershoot (34 %/20.63 %/43.75 %) and settling time (20.45 %/59.09 %/16.83 %) for variation in area-1 frequency/area-2 frequency/tie line power, respectively. The recommended control scheme is evidenced superior over numerous existing control techniques and provides least cost function in contrast to other control techniques. Additionally, it offers a highly stable performance under variable load conditions.

18.
Liver Int ; 2024 Aug 08.
Article in English | MEDLINE | ID: mdl-39115174

ABSTRACT

BACKGROUND AND AIMS: Chronic hepatitis D infection is the most severe form of viral hepatitis and can rapidly progress to cirrhosis or hepatocellular carcinoma. Despite recommendations for systematic screening of hepatitis B surface antigen (HBsAg)-positive individuals, data from real-world studies have reported a low frequency of hepatitis D (or delta) virus (HDV) screening. Our cross-sectional analysis evaluated the diagnostic cascade for hepatitis D infection in tertiary centres and described the characteristics of HDV-positive patients. METHODS: A total of 6772 individuals who tested HBsAg positive for the first time between 2018 and 2022 were retrospectively included. Demographic, clinical and laboratory data were analysed. RESULTS: A total of 5748 HBsAg-positive individuals (84.9%) were screened for HDV infection. The screening rate varied from 63% to 97% according to the screening strategy used in the centres including or not HDV reflex testing. The prevalence of HDV infection was 6.3%. HDV RNA levels were determined in 285 of the 364 (78.3%) HDV antibody screening-positive patients, and 167 (58.6%) had active HDV infection. 66.8% were males, with a mean age of 44.9 years. A total of 97.5% were born abroad, and 92.9% were HBeAg negative. At the time of diagnosis, HDV RNA levels were 6.0 Log UI/mL; 60.1% had alanine aminotransferase >40 U/L, and 56.3% had significant fibrosis (≥F2), including 41.6% with cirrhosis. The most common genotype was HDV-1 (75.4%). Coinfections were not uncommon: 7.4% were HIV positive, and 15.0% were HCV antibody positive. CONCLUSIONS: The present study highlights the need for increased screening and monitoring of HDV infection. Reflex testing helps to identify HDV-infected individuals.

19.
Int J Biol Macromol ; 277(Pt 2): 134355, 2024 Jul 30.
Article in English | MEDLINE | ID: mdl-39089543

ABSTRACT

Toward the development of a sustainable utilization strategy for adsorption materials, a starch-based adsorbent starch-chitosan-tannic acid (St-CTS-TA) with a three-dimensional (3D) structure was fabricated in water via electrostatic and hydrogen bonding reactions between St, CTS, and TA without using toxic reducing agents or special instruments. St-CTS-TA demonstrated a high specific surface area of 37 m2/g as well as a mesoporous/macroporous distribution ranging from 30 to 80 nm, which enhanced the mass transfer of adsorbate and the exposure of catechol groups in TA. The Langmuir isotherm adsorption model revealed that the highest adsorption capacities of St-CTS-TA for Fe3+ and Co2+ were 1678.2 and 944.8 mg/g, respectively. Surprisingly, the specific surface area of St-CTS-TA increased from 37 to 87 and 42 m2/g after Fe3+ and Co2+ adsorption, respectively, and the resulting St-CTS-TA-Fe and St-CTS-TA-Co could continuously adsorb basic fuchsin (BF) and rhodamine B (RhB). The adsorption capacities of St-CTS-TA-Fe and St-CTS-TA-Co for BF/RhB were found to be 1854.79/401.19 mg/g and 2229.77/537.49 mg/g, respectively, based on the Langmuir isotherm adsorption model.

20.
Ecol Evol ; 14(8): e70020, 2024 Aug.
Article in English | MEDLINE | ID: mdl-39114166

ABSTRACT

Animals occupying higher trophic levels can have disproportionately large influence on ecosystem structure and functioning, owning to intricate behavioral responses to their environment, but the effects of behavioral adaptations on aquatic ecosystem dynamics are underrepresented, especially in model studies. Here, we explore how adaptive behavior of fish can affect the dynamics of aquatics ecosystems. We frame fish behavior in the context of the central trade-off between feeding and predation, calculating the optimal level of feeding determined by ambient food availability and predation risk. To explore whole-ecosystem consequences of fish behavior, we embed our behavioral model within the Water Ecosystems Tool (WET), a contemporary end-to-end aquatic ecosystem model. The principle of optimality provides a robust and mechanistic framework for representing animal behavior that is relevant for complex models, and can provide a stabilizing effect on model dynamics. The model predicts an emergent functional response similar to Holling type III, but with richer dynamics and a more rigorous theoretical foundation. We show how adaptive fish behavior works to stabilize food web dynamics compared to a control model with no optimal behavior, and how changing the strength of the underlying trade-off has profound effects on trophic control and food web structure. Furthermore, we demonstrate how including fish behavior allows for an overall more realistic response of the model system to environmental perturbation in the form of nutrient enhancement. We discuss the structuring effects of behavioral adaptations in real ecosystems, and how approaches like this one may benefit aquatic ecological modeling. Our study further highlights how a mechanistic approach based on concepts from theoretical ecology can be successfully implemented in complex operational models resulting in improved dynamics and descriptive power.

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