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3.
Front Immunol ; 15: 1392546, 2024.
Article in English | MEDLINE | ID: mdl-38638430

ABSTRACT

Immunotherapy has been developed, which harnesses and enhances the innate powers of the immune system to fight disease, particularly cancer. PD-1 (programmed death-1) and PD-L1 (programmed death ligand-1) are key components in the regulation of the immune system, particularly in the context of cancer immunotherapy. PD-1 and PD-L1 are regulated by PTMs, including phosphorylation, ubiquitination, deubiquitination, acetylation, palmitoylation and glycosylation. PROTACs (Proteolysis Targeting Chimeras) are a type of new drug design technology. They are specifically engineered molecules that target specific proteins within a cell for degradation. PROTACs have been designed and demonstrated their inhibitory activity against the PD-1/PD-L1 pathway, and showed their ability to degrade PD-1/PD-L1 proteins. In this review, we describe how PROTACs target PD-1 and PD-L1 proteins to improve the efficacy of immunotherapy. PROTACs could be a novel strategy to combine with radiotherapy, chemotherapy and immunotherapy for cancer patients.


Subject(s)
B7-H1 Antigen , Neoplasms , Humans , B7-H1 Antigen/metabolism , Programmed Cell Death 1 Receptor/metabolism , Proteolysis Targeting Chimera , Neoplasms/drug therapy , Immunotherapy
4.
Int J Surg ; 110(5): 2939-2949, 2024 May 01.
Article in English | MEDLINE | ID: mdl-38376848

ABSTRACT

BACKGROUND: Although the COVID-19 pandemic has exerted potential impact on patients with glioblastomas (GBMs), it remains unclear whether the survival and its related risk factors of GBM patients would be altered or not during the period spanning from pre-COVID-19 to post-COVID-19 pandemic era. This study aimed to clarify the important issues above. METHODS: Two observational cohorts were utilized, including the nationwide American cohort from the Surveillance, Epidemiology, and End-Results (SEER) and the Chinese glioblastoma cohort (CGC) at our institution during 2018-2020. Demographics, tumour features, treatment regimens and clinical outcomes were collected. Cox regression model, competing risk model, and subgroup and sensitivity analysis were used to dynamically estimate the survival and its relevant risk factors over different diagnosis years from the pre-COVID-19 (2018 and 2019) to post-COVID-19 (2020) pandemic. Causal mediation analysis was further adopted to explore the potential relationship between risk factors and mortality. RESULTS: This study included 11321 GBM cases in SEER and 226 GBM patients in CGC, respectively. Instead of the diagnostic years of 2018-2020, the prognostic risk factors, such as advanced age, bilateral tumour and absence of comprehensive therapy (surgery combined with chemoradiotherapy), were identified to persistently affect GBM survival independently during the period from 2018 to 2020 in the SEER cohort (all P < 0.05). In CGC, lack of comprehensive therapy for GBM patients were restated as survival risk factors during the same timeframe. Causal mediation analysis showed that the effect of comprehensive therapy on all-cause mortality played a determinant role (direct effect value -0.227, 95% CI -0.248 to -0.207), which was partially mediated by age (9.11%) rather than tumour laterality. CONCLUSIONS: As the timeframe shifted from pre-COVID-19 to post-COVID-19 pandemic, survival of GBM patients remained stable, yet advanced age, bilateral tumours, and passive treatment continuingly impacted GBM survival. It is necessary to optimize the comprehensive treatment for GBM patients even in the post-pandemic era.


Subject(s)
Brain Neoplasms , COVID-19 , Glioblastoma , Humans , COVID-19/epidemiology , COVID-19/mortality , COVID-19/therapy , Glioblastoma/therapy , Glioblastoma/epidemiology , Glioblastoma/mortality , Male , Female , Middle Aged , China/epidemiology , United States/epidemiology , Risk Factors , Brain Neoplasms/epidemiology , Brain Neoplasms/therapy , Brain Neoplasms/mortality , Aged , Adult , Cohort Studies , SEER Program
5.
ACS Nano ; 2024 Feb 06.
Article in English | MEDLINE | ID: mdl-38318803

ABSTRACT

A rarely discussed phenomenon in the realm of photocatalytic materials involves the presence of gradient distributed dopants and defects from the interior to the surface. This intriguing characteristic has been successfully achieved in the case of ZnS through the incorporation of atomic monovalent copper ions (Cu+) and concurrent sulfur vacancies (Vs), resulting in a photocatalyst denoted as G-CZS1-x. Through the cooperative action of these atomic Cu dopants and Vs, G-CZS1-x significantly extends its photoabsorption range to encompass the full spectrum (200-2100 nm), which improves the solar utilization ability. This alteration enhances the efficiency of charge separation and optimizes Δ(H*) (free energy of hydrogen adsorption) to approach 0 eV for the hydrogen evolution reaction (HER). It is noteworthy that both surface-exposed atomic Cu and Vs act as active sites for photocatalysis. G-CZS1-x exhibits a significant H2 evolution rate of 1.01 mmol h-1 in the absence of a cocatalyst. This performance exceeds the majority of previously reported photocatalysts, exhibiting approximately 25-fold as ZnS, and 5-fold as H-CZS1-x with homogeneous distribution of equal content Cu dopants and Vs. In contrast to G-CZS1-x, the H adsorption on Cu sites for H-CZS1-x (ΔG(H*) = -1.22 eV) is excessively strong to inhibit the H2 release, and the charge separation efficiency for H-CZS1-x is relatively sluggish, revealing the positive role of a gradient distribution model of dopants and defects on activity enhancement. This work highlights the synergy of atomic dopants and defects in advancing photoactivity, as well as the significant benefit of the controllable distribution model of dopants and defects for photocatalysis.

6.
J Environ Manage ; 354: 120305, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38359630

ABSTRACT

Tracing lacustrine groundwater discharge (LGD) is essential for understanding the hydrological cycle and water chemistry behaviour of lakes. LGD usually exhibits large spatial variability, but there are few reports on quantitatively revealing the spatial patterns of LGD at the whole lake scale. This study investigated the spatial patterns of LGD in Daihai Lake, a typical closed inland lake in northern China, based on the stable isotopes (δ2H and δ18O) of groundwater, surface water, and sediment pore water (SPW). The results showed that there were significant differences between the δ2H and δ18O values of different water bodies in the Daihai Lake Basin: groundwater < SPW < lake water. The LGD through SPW was found to be an important recharge pathway for the lake. Accordingly, stable isotopes of SPW showed that LGD in the northeastern and northwestern of Daihai Lake was significantly greater both horizontally and vertically than that in the other regions, and the proportions of groundwater in SPW in these two regions were 55.53% and 29.84%, respectively. Additionally, the proportion of groundwater in SPW showed a significant increase with profile depth, and the proportion reached 100% at 50 cm below the sediment surface in the northeastern of the lake where the LGD intensity was strongest. The total LGD to Daihai Lake was 1.47 × 107 m3/a, while the LGD in the northeastern and northwestern of the lake exceeded 1.9 × 106 m3/a. This study provides new insights into assessing the spatial patterns of LGD and water resource management in lakes.


Subject(s)
Groundwater , Lakes , Isotopes , Water , Water Movements , China , Environmental Monitoring/methods
7.
Anal Methods ; 16(3): 411-419, 2024 01 18.
Article in English | MEDLINE | ID: mdl-38165144

ABSTRACT

The reliable and accurate detection of unauthorized additives in food is significant to prevent health risks. In recent years, surface-enhanced Raman spectroscopy (SERS) with fast, simple, and sensitive capabilities has been widely used for food safety analysis. In order to detect illegally added dye molecule rhodamine 6G and small molecule melamine in food, we have proposed a fast, convenient, and label-free SERS detection technology using flower-like Ag/ZnO as the SERS substrate. The structure and morphology of the flower-like Ag/ZnO were characterized by scanning electron microscopy, energy dispersive spectrometery, transmission electron microscopy, and X-ray diffraction analysis. We investigated the SERS effect and sensitivity of flower-like Ag/ZnO toward rhodamine 6G and melamine. The synergistic effect of flower-like Ag/ZnO provides high SERS activity for the detection of rhodamine 6G and melamine at the lowest detection concentrations of 0.5 ng mL-1 and 1.0 ng mL-1, respectively. Therefore, flower-like Ag/ZnO with good sensitivity and uniformity has potential for improving the detection of illegal food additives.


Subject(s)
Rhodamines , Spectrum Analysis, Raman , Triazines , Zinc Oxide , Zinc Oxide/chemistry , Silver/chemistry
8.
Cell Mol Immunol ; 21(1): 47-59, 2024 01.
Article in English | MEDLINE | ID: mdl-38049523

ABSTRACT

A highly immunosuppressive tumor microenvironment (TME) and the presence of the blood‒brain barrier are the two major obstacles to eliciting an effective immune response in patients with high-grade glioma (HGG). Here, we tried to enhance the local innate immune response in relapsed HGG by intracranially injecting poly(I:C) to establish a robust antitumor immune response in this registered clinical trial (NCT03392545). During the follow-up, 12/27 (44.4%) patients who achieved tumor control concomitant with survival benefit were regarded as responders in our study. We found that the T-cell receptor (TCR) repertoire in the TME was reshaped after poly(I:C) treatment. Based on the RNA-seq analysis of tumor samples, the expression of annexin A1 (ANXA1) was significantly upregulated in the tumor cells of nonresponders, which was further validated at the protein level. In vitro and in vivo experiments showed that ANXA1 could induce the production of M2-like macrophages and microglia via its surface receptor formyl peptide receptor 1 (FPR1) to establish a Treg cell-driven immunosuppressive TME and suppress the antitumor immune response facilitated by poly(I:C). The ANXA1/FPR1 signaling axis can inhibit the innate immune response of glioma patients by promoting an anti-inflammatory and Treg-driven TME. Moreover, ANXA1 could serve as a reliable predictor of response to poly(I:C), with a notable predictive accuracy rate of 92.3%. In light of these notable findings, this study unveils a new perspective of immunotherapy for gliomas.


Subject(s)
Annexin A1 , Glioma , Humans , Annexin A1/metabolism , Anti-Inflammatory Agents , Immunity , Toll-Like Receptor 3/metabolism , Tumor Microenvironment
9.
Small ; 20(22): e2308957, 2024 May.
Article in English | MEDLINE | ID: mdl-38111984

ABSTRACT

Atomically dispersed metal and nitrogen co-doped carbon catalysts (M-N-C) have been attracting tremendous attentions thanks to their unique MNx active sites and fantastic catalytic activities in advanced oxidation technologies (AOTs) for water remediation. However, precisely tailoring the microenvironment of active sites at atomic level is still an intricate challenge so far, and understanding of the non-radical mechanisms in persulfate activation exists many uncertainties. In this review, latest developments on the microenvironment modulation strategies of atomically dispersed M-N-C catalysts including regulation of central metal atoms, regulation of coordination numbers, regulation of coordination heteroatoms, and synergy between single-atom catalysts (SACs) with metal species are systematically highlighted and discussed. Afterwards, progress and underlying limitations about the typical non-radical pathways from production of singlet oxygen, electron transfer mechanism to generation of high-valent metal species are well demonstrated to inspire intrinsic insights about the mechanisms of M-N-C/persulfate systems. Lastly, perspectives for the remaining challenges and opportunities about the further development of carbon-based SACs in environment remediation are also pointed out. It is believed that this review will be much valuable for the further design of active sites in M-N-C/persulfate catalytic systems and promote the wide application of SACs in various fields.

10.
J Neurooncol ; 165(3): 547-559, 2023 Dec.
Article in English | MEDLINE | ID: mdl-38095773

ABSTRACT

PURPOSE: This study aimed to assess the ability of [11C]methionine (MET) PET in distinguishing between tumor progression (TP) and treatment-related changes (TRCs) among different types of adult-type diffuse gliomas according to the 2021 World Health Organization classification and predict overall survival (OS). METHODS: We retrospectively selected 113 patients with adult-type diffuse gliomas with suspected TP who underwent MET PET imaging. Maximum and mean tumor-to-background ratios (TBRmax, TBRmean) and metabolic tumor volume (MTV) were calculated. Diagnoses were verified by histopathology (n = 50) or by clinical/radiological follow-up (n = 63). The diagnostic performance of MET PET parameters was evaluated through receiver operating characteristic (ROC) analysis and area under the curve (AUC) calculation. Survival analysis employed the Kaplan-Meier method and Cox proportional-hazards regression. RESULTS: TP and TRCs were diagnosed in 76 (67%) and 37 (33%) patients, respectively. ROC analysis revealed TBRmax had the best performance in differentiating TP from TRCs with a cut-off of 1.96 in IDH-mutant astrocytoma (AUC, 0.87; sensitivity, 93%; specificity 69%), 1.80 in IDH-mutant and 1p/19q-codeleted oligodendroglioma (AUC, 0.96; sensitivity, 100%; specificity, 89%), and 2.13 in IDH wild-type glioblastoma (AUC, 0.89; sensitivity, 89%; specificity, 78%), respectively. On multivariate analysis, higher TBRmean and MTV were significantly correlated with shorter OS in all IDH-mutant gliomas, as well as in IDH-mutant astrocytoma subgroup. CONCLUSION: This work confirms that MET PET has varying diagnostic performances in distinguishing TP from TRCs within three types of adult-type diffuse gliomas, and highlights its high diagnostic accuracy in IDH-mutant and 1p/19q-codeleted oligodendroglioma and potential prognostic value for IDH-mutant gliomas, particularly IDH-mutant astrocytoma.


Subject(s)
Astrocytoma , Brain Neoplasms , Glioma , Oligodendroglioma , Adult , Humans , Methionine , Brain Neoplasms/diagnostic imaging , Brain Neoplasms/genetics , Brain Neoplasms/therapy , Retrospective Studies , Glioma/diagnostic imaging , Glioma/genetics , Glioma/therapy , Racemethionine , Positron-Emission Tomography , Isocitrate Dehydrogenase/genetics , Mutation
11.
Eur Radiol ; 2023 Nov 16.
Article in English | MEDLINE | ID: mdl-37968476

ABSTRACT

OBJECTIVE: Calcification is a hallmark characteristic of oligodendroglioma (ODG) that may be used as a diagnostic factor, but its prognostic implications remain unclear. This study aimed to investigate the features of calcified ODGs and to evaluate the differences in survival between patients with calcified and noncalcified ODGs. METHODS: We retrospectively reviewed the records of 305 consecutive patients who were diagnosed with IDH-mutant, 1p/19q codeleted ODG at our institution from July 2009 to August 2020. Patients with intratumoral calcification were identified. The clinical, radiologic, and molecular features of the patients in the calcified group and noncalcified group were recorded. Univariate and multivariate analyses were performed to identify prognostic factors. RESULTS: Of the 305 patients, 112 (36.7%) were confirmed to have intratumoral calcification. Compared to ODGs without calcification, ODGs with calcifications had a larger tumor diameter; lower degree of resection; higher tumor grade; higher MGMT methylation level; higher Ki-67 index; and higher rates of midline crossing, enhancement, cyst, and 1q/19p copolysomy, and patients with calcification were more likely to receive chemoradiotherapy. ODGs with T2 hypointense calcification had a higher Hounsfield unit (HU) value on CT scans, and a lower degree of resection. Patients with T2 hypointense calcification ODGs had a shorter survival than those with non-hypointense calcification ODGs. ODGs with calcification and cysts showed a higher Ki-67 index, tumor grade, and enhanced rate, and the patients had an unfavorable overall survival (OS). Calcification was found to be a negative prognostic factor for both progression-free survival (PFS) and OS by univariate analysis, which was confirmed by the Cox proportional hazard model. CONCLUSIONS: Calcification is a useful negative prognostic factor for PFS and OS in patients with ODGs and could therefore be helpful in guiding personalized treatment and predicting patient prognosis. CLINICAL RELEVANCE STATEMENT: Calcification can serve as an independent prognostic factor for patients with oligodendroglioma and shows a vital role in guiding individualized treatment. KEY POINTS: • Intratumoral calcification is an independent negative prognostic risk factor for progression-free survival and overall survival in oligodendroglioma patients. • Calcifications in oligodendroglioma can be divided into hypointense and non-hypointense subtypes based on T2-weighted imaging, and patients with T2-hypointense calcification oligodendrogliomas have worse prognosis. • Calcification concurrent with cysts indicates a more aggressive phenotype of oligodendrogliomas and a significantly reduced survival rate.

13.
Nat Metab ; 5(11): 1887-1910, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37903887

ABSTRACT

Senescent cells remain metabolically active, but their metabolic landscape and resulting implications remain underexplored. Here, we report upregulation of pyruvate dehydrogenase kinase 4 (PDK4) upon senescence, particularly in some stromal cell lines. Senescent cells display a PDK4-dependent increase in aerobic glycolysis and enhanced lactate production but maintain mitochondrial respiration and redox activity, thus adopting a special form of metabolic reprogramming. Medium from PDK4+ stromal cells promotes the malignancy of recipient cancer cells in vitro, whereas inhibition of PDK4 causes tumor regression in vivo. We find that lactate promotes reactive oxygen species production via NOX1 to drive the senescence-associated secretory phenotype, whereas PDK4 suppression reduces DNA damage severity and restrains the senescence-associated secretory phenotype. In preclinical trials, PDK4 inhibition alleviates physical dysfunction and prevents age-associated frailty. Together, our study confirms the hypercatabolic nature of senescent cells and reveals a metabolic link between cellular senescence, lactate production, and possibly, age-related pathologies, including but not limited to cancer.


Subject(s)
Lactic Acid , Neoplasms , Protein Kinases , Up-Regulation , Cellular Senescence
14.
Environ Pollut ; 338: 122651, 2023 Dec 01.
Article in English | MEDLINE | ID: mdl-37797925

ABSTRACT

Frequent outbreaks of harmful cyanobacterial blooms and the microcystins (MCs) they produce seriously affect the survival of aquatic organisms. Interactions between gut microbiota and hosts often play crucial roles in driving the adaptation of aquatic organisms to environmental changes. In this study, we investigated the phenotypic indicators of the freshwater gastropod Bellamya aeruginosa, after uptake of Microcystis aeruginosa and explored its gut microbial composition and gut metabolites in response to toxic cyanobacterial stress. Results showed that the MCs concentration in the hepatopancreas of snails fed with toxic cyanobacteria decreased from 2.64 ± 0.14 µg·g-1 on day 7 to 1.16 ± 0.10 µg·g-1 on day 14. The compositions of the intestinal microbiota of snails fed with different algae significantly differed, and the relative abundance of gut microbes such as Lactobacillus and Sphingobium significantly increased after feeding toxic cyanobacteria. Significant differences also existed in intestinal metabolites, the relative abundance of the following metabolites significantly increased: l-proline, 5,6-DHET, stachyose, raffinose, and 3-isopropylmalate. Sankey network diagrams showing links between gut microbes and gut metabolites. The association of Lactobacillus and Sphingobium with amino acids may be related to host tolerance to toxicity, and the linkages of gut microbes with metabolites such as levan, imidazolepropionic acid, and eicosanoids may be associated with involvement in host immune responses. The association of microbes with stachyose and raffinose can help the host to regulate energy homeostasis. These results reveal the underlying mechanisms of gut microbes in the snail adaptation to toxic cyanobacterial stress. This study could be great important for gaining new insights into toxic cyanobacteria-induced changes in snail gut microbes and metabolites and their roles in snail adaptation to toxic cyanobacterial stress, and may provide important insights into the use of freshwater gastropods for the prevention and control of cyanobacterial blooms.


Subject(s)
Cyanobacteria , Gastrointestinal Microbiome , Gastropoda , Microcystis , Animals , Raffinose/metabolism , Cyanobacteria/metabolism , Microcystis/metabolism , Fresh Water , Microcystins/toxicity , Microcystins/metabolism
15.
Chem Commun (Camb) ; 59(75): 11280-11283, 2023 Sep 19.
Article in English | MEDLINE | ID: mdl-37665259

ABSTRACT

Transition metal ions (M = Ag+, Cu2+, Co2+, and Cr3+) are surface or homogeneously doped into ZnS via facile cation-exchange reaction, and while Ag+ and Cu2+ doping does not induce sulphur vacancies (Vs) or zinc vacancies (VZn), Co2+ and Cr3+ doping induces Vs. The surface doped catalysts exhibit greatly higher activity than the ZnS and homogenous doped catalysts for H2 evolution and CO2 reduction. The important role of the doping state on affecting the photo-absorption, carrier separation efficiency, and photoreaction kinetics has been systemically investigated and proposed. This work sheds light on the future design and fabrication of high-performance photocatalysts by element doping.

16.
Int J Public Health ; 68: 1606074, 2023.
Article in English | MEDLINE | ID: mdl-37637486

ABSTRACT

Objective: In December 2022, the Chinese government announced the further optimization of the implementation of the prevention and control measures of COVID-19. We aimed to assess internet-using public expression and sentiment toward COVID-19 in the relaxation of control measures in China. Methods: We used a user-simulation-like web crawler to collect raw data from Sina-Weibo and then processed the raw data, including the removal of punctuation, stop words, and text segmentation. After performing the above processes, we analyzed the data in two aspects. Firstly, we used the Latent Dirichlet Allocation (LDA) model to analyze the text data and extract the theme. After that, we used sentiment analysis to reveal the sentiment trend and the geographical spatial sentiment distribution. Results: A total of five topics were extracted according to the LDA model, namely, Complete liberalization, Resource supply, Symptom, Knowledge, and Emotional Outlet. Furthermore, sentiment analysis indicates that while the percentages of positive and negative microblogs fluctuate over time, the overall quantity of positive microblogs exceeds that of negative ones. Meanwhile, the geographical dispersion of public sentiment on internet usage exhibits significant regional variations and is subject to multifarious factors such as economic conditions and demographic characteristics. Conclusion: In the face of the relaxation of COVID-19 control measures, although concerns arise among people, they continue to encourage and support each other.


Subject(s)
COVID-19 , Social Media , Humans , Sentiment Analysis , COVID-19/epidemiology , COVID-19/prevention & control , Internet , Internet Use
17.
J Neurosurg ; 139(4): 953-964, 2023 10 01.
Article in English | MEDLINE | ID: mdl-37561905

ABSTRACT

OBJECTIVE: Despite the controversy surrounding brain invasion (BI) as the sole indicator used to diagnose atypical meningioma, this criterion was still incorporated in the 2021 WHO classification scheme. In this study, the authors investigated the reproducibility of this prognostic effect and the impact of BI on the prognosis in otherwise benign meningioma (benign meningioma with BI). METHODS: Patients (n = 1006) with a pathological diagnosis of benign or atypical meningioma according to the latest WHO classification criteria were enrolled in this study. In patients with atypical meningioma, the cases were further categorized as benign meningioma with BI and classical atypical meningioma. Clinical, pathological, and follow-up data were collected. Kaplan-Meier curves were compared with a log-rank test, and univariate and multivariate analyses were performed. RESULTS: The study patient cohort included 282 (28.0%) individuals who were pathologically confirmed as having BI among all 1006 patients with benign or atypical meningioma. A significant difference in recurrence-free survival was observed between patients who had benign meningioma with BI and those who had classical atypical meningioma (p < 0.001), as well as between patients with benign meningiomas and those without BI (p = 0.003). Multivariate Cox analysis indicated that BI was independently associated with increased risk of relapse in the entire population (HR 1.46, 95% CI 1.01-2.12, p = 0.049) and in the atypical meningioma subcohort (HR 2.21, 95% CI 1.32-3.71, p = 0.003), as well as the benign meningioma with and without BI subcohorts (HR 1.89, 95% CI 1.01-3.56, p = 0.049). Moreover, patients with classical atypical meningiomas had a risk of relapse four times higher than those who had benign meningioma with BI (p < 0.001). CONCLUSIONS: The findings demonstrate that benign meningioma with BI typically has an intermediate prognosis and can be differentiated from benign meningioma and classical atypical meningioma, which suggests that the importance of the diagnostic effect of BI is insufficiently accounted for in grading of atypical meningioma. Increased emphasis on the presence of BI in patients with atypical meningioma may be helpful in postsurgical decision-making and facilitating improvements in individual therapy.


Subject(s)
Meningeal Neoplasms , Meningioma , Humans , Meningioma/surgery , Meningeal Neoplasms/surgery , Reproducibility of Results , Neoplasm Recurrence, Local , Prognosis , Recurrence , Brain/pathology , Retrospective Studies
19.
J Environ Manage ; 344: 118314, 2023 Oct 15.
Article in English | MEDLINE | ID: mdl-37343475

ABSTRACT

Although saline aquatic ecosystems are significant emitters of greenhouse gases (GHGs), dynamic changes in GHGs at the sediment-water interface remain unclear. The present investigation carried out a total of four sampling campaigns in Daihai Lake, which is a eutrophic saline lake situated in a semi-arid area of northern China. The aim of this study was to investigate the spatio-temporal dynamics of carbon dioxide (CO2) and methane (CH4) fluxes at the sediment-water interface and the influencing factors. The mean concentrations of porewater CO2 and CH4 were 44.98 ± 117.99 µmol L-1 and 124.36 ± 97.00 µmol L-1, far exceeding those in water column of 11.14 ± 2.16 µmol L-1 and 0.33 ± 0.23 µmol L-1, respectively. The CO2 and CH4 fluxes at the sediment-water interface (FS-WCO2 and FS-WCH4) exhibited significant spatial and temporal variations, with mean values of 9.24 ± 13.84 µmol m-2 d-1 and 3.53 ± 4.36 µmol m-2 d-1, respectively, indicating that sediment is the source of CO2 and CH4 in the water column. However, CO2 and CH4 fluxes were much lower than those measured at the water-air interface in a companion study (17.54 ± 14.54 mmol m-2d-1 and 0.50 ± 0.50 mmol m-2d-1, respectively), indicating that the diffusive flux of gases at the sediment-water interface was not the primary source of CO2 and CH4 emissions to the atmosphere. Regression and correlation analyses revealed that salinity (Sal) and nutrients were the most influential factors on porewater gas concentrations, and that gas fluxes increased with increasing gas concentrations and porosity. The microbial activity of sediment is greatly affected by nutrients and Sal. Additionally, Sal has the ability to regulate biogeochemical processes, thereby regulating GHG emissions. The present investigation addresses the research gap concerning GHG emissions from sediments of eutrophic saline lakes. The study suggests that controlling the eutrophication and salinization of lakes could be a viable strategy for reducing carbon emissions from lakes. However, further investigations are required to establish more conclusive results.


Subject(s)
Carbon Dioxide , Greenhouse Gases , Carbon Dioxide/analysis , Lakes/analysis , Ecosystem , Water/analysis , Greenhouse Gases/analysis , Methane/analysis , China
20.
Molecules ; 28(12)2023 Jun 12.
Article in English | MEDLINE | ID: mdl-37375258

ABSTRACT

Photocatalytic CO2 reduction to valuable hydrocarbon solar fuel is of great significance but still challenging. Strong CO2 enrichment ability and easily adjustable structures make metal-organic frameworks (MOFs) potential photocatalysts for CO2 conversion. Even though pure MOFs have the potential for photoreduction of CO2, the efficiency is still quite low due to rapid photogenerated electron-hole recombination and other drawbacks. In this work, graphene quantum dots (GQDs) were in situ encapsulated into highly stable MOFs via a solvothermal method for this challenging task. The GQDs@PCN-222 with encapsulated GQDs showed similar Powder X-ray Diffraction (PXRD) patterns to PCN-222, indicating the retained structure. The porous structure was also retained with a Brunauer-Emmett-Teller (BET) surface area of 2066 m2/g. After incorporation of GQDs, the shape of GQDs@PCN-222 particles remained, as revealed by the scanning electron microscope (SEM). As most of the GQDs were covered by thick PCN-222, it was hard to observe those GQDs using a transmission electron microscope (TEM) and a high-resolution transmission electron microscope (HRTEM) directly, the treatment of digested GQDs@PCN-222 particles by immersion in a 1 mM aqueous KOH solution can make the incorporated GQDs visible in TEM and HRTEM. The linker, deep purple porphyrins, make MOFs a highly visible light harvester up to 800 nm. The introduction of GQDs inside PCN-222 can effectively promote the spatial separation of the photogenerated electron-hole pairs during the photocatalytic process, which was proved by the transient photocurrent plot and photoluminescence emission spectra. Compared with pure PCN-222, the obtained GQDs@PCN-222 displayed dramatically enhanced CO production derived from CO2 photoreduction with 147.8 µmol/g/h in a 10 h period under visible light irradiation with triethanolamine (TEOA) as a sacrificial agent. This study demonstrated that the combination of GQDs and high light absorption MOFs provides a new platform for photocatalytic CO2 reduction.

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