ETHNOPHARMACOLOGICAL RELEVANCE: Taohong Siwu Decoction (TSD), a classic traditional Chinese medicine formula, is used for the treatment of vascular diseases, including vascular dementia (VD). However, the mechanisms remain unclear. AIM OF STUDY: This study aimed to investigate whether TSD has a positive effect on cognitive impairment in VD rats and to confirm that the mechanism of action is related to the Endoplasmic Reticulum stress (ERs) and cell apoptosis signaling pathway. MATERIALS AND METHODS: A total of 40 male adult Sprague-Dawley rats were divided into four groups: sham-operated group (Sham), the two-vessel occlusion group (2VO), the 2VO treated with 4.5g/kg/d TSD group (2VO+TSD-L), the 2VO treated with 13.5g/kg/d TSD group (2VO+TSD-H). The rats underwent either 2VO surgery or sham surgery. Postoperative TSD treatment was given for 4 consecutive weeks. Behavioral tests were initiated at the end of gastrulation. Open-field test (OFT) was used to detect the activity level. The New Object Recognition test (NOR) was used to test long-term memory. The Morris water maze (MWM) test was used to examine the foundation of spatial learning and memory. As a final step, the hippocampus was taken for molecular testing. The protein levels of GRP78 (Bip), p-PERK, PERK, IRE1α, p-IRE1α, ATF6, eIF2α, p- eIF2α, ATF4, XBP1, Bcl-2 and Bax were determined by western blot. Immunofluorescence visualizes molecular expression. RESULTS: In the OFT, residence time in the central area was significantly longer in both TSD treatment groups compared to the 2VO group. In the NOR, the recognition index was obviously elevated in both TSD treatment groups. The 2VO group had a significantly longer escape latency and fewer times in crossing the location of the platform compared with the Sham group in MWM. TSD treatment reversed this notion. Pathologically, staining observations confirmed that TSD inhibited hippocampal neuronal loss and alleviated the abnormal reduction of the Nissl body. In parallel, TUNEL staining illustrated that TSD decelerated neuronal apoptosis. Western Blot demonstrated that TSD reduces the expression of ERs and apoptotic proteins. CONCLUSION: In this study, the significant ameliorative effect on cognitive impairment of TSD has been determined by comparing the behavioral data of the 4 groups of rats. Furthermore, it was confirmed that this effect of TSD was achieved by suppressing the ERs-mediated apoptosis signaling pathway.
Nature continually refines its processes for optimal efficiency, especially within biological systems. This article explores the collaborative efforts of researchers worldwide, aiming to mimic nature's efficiency by developing smarter and more effective nanoscale technologies and biomaterials. Recent advancements highlight progress and prospects in leveraging engineered nucleic acids and proteins for specific tasks, drawing inspiration from natural functions. The focus is developing improved methods for characterizing, understanding, and reprogramming these materials to perform user-defined functions, including personalized therapeutics, targeted drug delivery approaches, engineered scaffolds, and reconfigurable nanodevices. Contributions from academia, government agencies, biotech, and medical settings offer diverse perspectives, promising a comprehensive approach to broad nanobiotechnology objectives. Encompassing topics from mRNA vaccine design to programmable protein-based nanocomputing agents, this work provides insightful perspectives on the trajectory of nanobiotechnology toward a future of enhanced biomimicry and technological innovation.
Both clinical and animal studies showed that the impaired functions of the orbitofrontal cortex (OFC) underlie the compulsive drug-seeking behavior of drug addiction. However, the functional changes of the microcircuit in the OFC and the underlying molecular mechanisms in drug addiction remain elusive, and little is known for whether microcircuits in the OFC contributed to drug addiction-related behaviors. Utilizing the cocaine-induced conditioned-place preference model, we found that the malfunction of the microcircuit led to disinhibition in the OFC after cocaine withdrawal. We further showed that enhanced Somatostatin-Parvalbumin (SST-PV) inhibitory synapse strength changed microcircuit function, and SST and PV inhibitory neurons showed opposite contributions to the drug addiction-related behavior of mice. Brevican of the perineuronal nets of PV neurons regulated SST-PV synapse strength, and the knockdown of Brevican alleviated cocaine preference. These results reveal a novel molecular mechanism of the regulation of microcircuit function and a novel circuit mechanism of the OFC in gating cocaine preference.
BACKGROUND: The aqueous humor, a transparent fluid secreted by the ciliary body, supports the lens of the eyeball. In this study, we analyzed the cytokine and chemokine profiles within the aqueous humor of the contralateral eye post-implantation of an implantable collamer lens (ICL) to evaluate potential subclinical inflammation in the second eye subsequent to ICL implantation in the first eye. METHODS: Aqueous humor samples were procured from both eyes of 40 patients (totaling 80 eyes) prior to bilateral ICL insertion. Subsequently, a comprehensive statistical analysis was conducted using the Luminex assay to quantify 30 different cytokines in these samples. RESULTS: Compared to the first eye, the aqueous humor of the second eye demonstrated decreased concentrations of IFN-γ (P = 0.038), IL-13 (P = 0.027), IL-17/IL-17 A (P = 0.012), and IL-4 (P = 0.025). No significant differences were observed in other cytokine levels between the two groups. Patients were then categorized based on the postoperative rise in intraocular pressure (IOP) in the first eye. The group with elevated IOP displayed elevated levels of EGF in the aqueous humor of the first eye (P = 0.013) and higher levels of PDGF-AB/BB in the aqueous humor of the second eye (P = 0.032) compared to the group with normal IOP. Within the elevated IOP group, the levels of EGF (P = 0.013) and IL-17/IL-17 A (P = 0.016) in the aqueous humor were lower in the second eye than in the first eye. In the normal IOP group, cytokine levels did not differ notably between eyes. CONCLUSION: Following sequential ICL implantation, it appears that a protective response may be activated to mitigate subclinical inflammation in the second eye induced by the initial implantation in the first eye. Additionally, the increase in IOP subsequent to surgery in the first eye may correlate with the presence of inflammatory mediators in the aqueous humor.
Background: Crush Syndrome (CS), a severe trauma resulting from prolonged muscle compression, is commonly seen in large-scale disasters such as earthquakes. It not only causes localized tissue damage but also triggers electrolyte imbalances, particularly hyperkalemia, increasing the risk of early mortality. This study aims to assess the early intervention effects of Sodium Zirconium Cyclosilicate (SZC) on hyperkalemia in rat CS model. Methods: A rat CS model was established using a self-developed multi-channel intelligent small-animal crush injury platform. Rats in the experimental groups were treated with varying doses of SZC before compression and immediately post-decompression. The efficacy of SZC was evaluated by continuous monitoring of blood potassium levels and survival rates. Serum creatinine (Cre) and blood urea nitrogen (BUN) levels were analyzed, and renal damage was assessed through histopathological examination. Results: SZC treatment significantly reduced blood potassium levels and improved survival rates in rats. Compared to the placebo group, the SZC-treated rats showed a significant decrease in blood potassium levels at 6 and 12 h post-decompression, maintaining lower levels at 24 h. Biochemical analysis indicated no significant impact of SZC on renal function, with no notable differences in Cre and BUN levels between groups. Histopathological findings revealed similar levels of renal damage in both groups. Conclusion: SZC demonstrates significant early intervention effects on hyperkalemia in a rat model of crush injury, effectively improving survival rates without adverse effects on renal function. These results provide a new strategic direction for the clinical treatment of Crush Syndrome and lay the foundation for future clinical applications.
INTRODUCTION: IL-17 has been described as a pro-inflammatory cytokine that is relevant in the seronegative spondylarthritides with IL-17 targeted therapies being licensed for their treatment.There is evidence to demonstrate that IL-17 is found in RA joints and contributes to the pro-inflammatory cascade. This results in synovial hyperplasia and osteoclastogenesis thus causing joint destruction and bony erosions. AREAS COVERED: This review article summarizes trials that have studied the use of IL-17 targeted therapies in RA patients who have failed conventional synthetic disease-modifying therapy (C-DMARDS) and biologic DMARDS. EXPERT OPINION: The trials that have studied IL-17 inhibitors in RA patients have only shown a modest improvement in disease activity. In several trials, the primary endpoint was not achieved whilst in others, when comparing with existing licensed biologics for RA, did not demonstrate any superiority.Tissue Necrosis Factor-alpha (TNF-α) likely plays more of a pivotal role in the pathogenesis of RA with IL-17 having a synergistic effect. Therefore, in our opinion, IL-17 inhibitors as an independent therapy for RA are less likely to provide a cost-effective benefit. There may be scope to potentially combine it with TNF-α-inhibitors (TNF-i), but this requires further research especially with the potential concerns related to increased immunosuppression.
Constipation is a common gastrointestinal condition, which may occur at any age and affects countless people. The search for new treatments for constipation is ongoing as current drug treatments fail to provide fully satisfactory results. In recent years, probiotics have attracted much attention because of their demonstrated therapeutic efficacy and fewer side effects than pharmaceutical products. Many studies attempted to answer the question of how probiotics can alleviate constipation. It has been shown that different probiotic strains can alleviate constipation by different mechanisms. The mechanisms on probiotics in relieving constipation were associated with various aspects, including regulation of the gut microbiota composition, the level of short-chain fatty acids, aquaporin expression levels, neurotransmitters and hormone levels, inflammation, the intestinal environmental metabolic status, neurotrophic factor levels and the body's antioxidant levels. This paper summarizes the perception of the mechanisms on probiotics in relieving constipation and provides some suggestions on new research directions.
The CRISPR/Cas nucleases system is widely considered the most important tool in genome engineering. However, current methods for predicting on/off-target effects and designing guide RNA (gRNA) rely on purely data-driven approaches or focus solely on the system's thermal equilibrium properties. Nonetheless, experimental evidence suggests that the process is kinetically controlled rather than being in equilibrium. In this study, we utilized a vast amount of available data and combined random forest, a supervised ensemble learning algorithm, and free energy landscape analysis to investigate the kinetic pathways of R-loop formation in the CRISPR/Cas9 system and the intricate molecular interactions between DNA and the Cas9 RuvC and HNH domains. The study revealed (a) a novel three-state kinetic mechanism, (b) the unfolding of the activation state of the R-loop being the most crucial kinetic determinant and the key predictor for on- and off-target cleavage efficiencies, and (c) the nucleotides from positions +13 to +16 being the kinetically critical nucleotides. The results provide a biophysical rationale for the design of a kinetic strategy for enhancing CRISPR/Cas9 gene editing accuracy and efficiency.
Tapetum, the innermost layer of the anther wall, provides essential nutrients and materials for pollen development. Timely degradation of anther tapetal cells is a prerequisite for normal pollen development in flowering plants. Tapetal cells facilitate male gametogenesis by providing cellular contents after highly coordinated programmed cell death (PCD). Tapetal development is regulated by a transcriptional network. However, the signaling pathway(s) involved in this process are poorly understood. In this study, we report that a mitogen-activated protein kinase (MAPK) cascade composed of OsYDA1/OsYDA2-OsMKK4-OsMPK6 plays an important role in tapetal development and male gametophyte fertility. Loss of function of this MAPK cascade leads to anther indehiscence, enlarged tapetum, and aborted pollen grains. Tapetal cells in osmkk4 and osmpk6 mutants exhibit an increased presence of lipid body-like structures within the cytoplasm, which is accompanied by a delayed occurrence of PCD. Expression of a constitutively active version of OsMPK6 (CA-OsMPK6) can rescue the pollen defects in osmkk4 mutants, confirming that OsMPK6 functions downstream of OsMKK4 in this pathway. Genetic crosses also demonstrated that the MAPK cascade sporophyticly regulates pollen development. Our study reveals a novel function of rice MAPK cascade in plant male reproductive biology.
The Presenilin (Psn) gene is closely related to aging, but it is still unclear the role of Psn genes in skeletal muscle. Here, the Psn-UAS/Mhc-GAL4 system in Drosophila was used to regulate muscle Psn overexpression(MPO) and muscle Psn knockdown(MPK). Drosophila were subjected to endurance exercise from 4 weeks to 5 weeks old. The results showed that MPO and exercise significantly increased climbing speed, climbing endurance, lifespan, muscle SOD activity, Psn expression, Sirt1 expression, PGC-1α expression, and armadillo (arm) expression in aged Drosophila, and they significantly decreased muscle malondialdehyde levels. Interestingly, when the Psn gene is knockdown by 0.78 times, the PGC-1α expression and arm expression were also down-regulated, but the exercise capacity and lifespan were increased. Furthermore, exercise combined with MPO further improved the exercise capacity and lifespan. MPK combined with exercise further improves the exercise capacity and lifespan. Thus, current results confirmed that the muscle Psn gene was a vital gene that contributed to the healthy aging of skeletal muscle since whether it was overexpressed or knocked down, the aging progress of skeletal muscle structure and function was slowed down by regulating the activity homeostasis of Sirt1/PGC-1α pathway and Psn/arm pathway. Exercise enhanced the function of the Psn gene to delay skeletal muscle aging by up regulating the activity of the Sirt1/PGC-1α pathway and Psn/arm pathway.
Longevity , Muscle, Skeletal , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha , Physical Conditioning, Animal , Sirtuin 1 , Animals , Sirtuin 1/metabolism , Sirtuin 1/genetics , Muscle, Skeletal/metabolism , Muscle, Skeletal/physiology , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/genetics , Longevity/genetics , Drosophila Proteins/genetics , Drosophila Proteins/metabolism , Signal Transduction , Healthy Aging/genetics , Healthy Aging/metabolism , Healthy Aging/physiology , Transcription Factors/metabolism , Transcription Factors/genetics , Aging/physiology , Aging/genetics , Aging/metabolism
Purpose: To investigate the CYP2C19 genotype distribution and allelic frequency among the Zhuang and Han schizophrenic populations in Guangxi, examine the correlation between CYP2C19 genetic variants and standardized blood levels of Valproic Acid (VPA) in schizophrenic patients, and evaluate the effects of age, gender, and Body Mass Index (BMI) on standardized VPA blood concentrations. Patients and Methods: Between February and December 2022, 192 Zhuang and Han schizophrenia patients treated with VPA were studied. Steady-state VPA concentrations were determined using homogeneous enzyme immunoassays, and CYP2C19 *1, *2, and *3 loci via q-PCR. CYP2C19 genotype distributions between Zhuang and Han groups in Nanning were compared using chi-square tests and contrasted with other ethnicities. Non-parametric tests analyzed VPA variations, identifying critical factors through multivariate stepwise regression. Results: The study identified five CYP2C19 genotypes at the *2 and *3 loci, with the *3/*3 genotype absent in both cohorts. The CYP2C19 distribution in Guangxi Zhuang and Han mirrors, yet diverges significantly from Hui and Kazakh groups. Among 192 subjects, VPA blood levels remained consistent across metabolic types and ages 18-60 but varied significantly by gender. Multivariate analysis revealed gender and BMI as significant factors, overshadowing CYP2C19 genotype and age. Conclusion: In Guangxi, CYP2C19 genetic variants in Zhuang and Han schizophrenia patients demonstrate statistically indistinguishable allelic and metabolic distributions. Gender and BMI can influence standardized VPA blood concentrations in schizophrenia patients. However, in our study cohort, the CYP2C19 genotype and age are not the primary determinants of standardized VPA blood levels.
B7-H1 Antigen , Biomarkers, Tumor , Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Humans , Carcinoma, Non-Small-Cell Lung/pathology , Carcinoma, Non-Small-Cell Lung/drug therapy , Carcinoma, Non-Small-Cell Lung/mortality , Carcinoma, Non-Small-Cell Lung/genetics , Lung Neoplasms/pathology , Lung Neoplasms/mortality , B7-H1 Antigen/antagonists & inhibitors , Biomarkers, Tumor/genetics , Prognosis , Immune Checkpoint Inhibitors/therapeutic use
This mini-review reports the recent advances in biomolecular simulations, particularly for nucleic acids, and provides the potential effects of the emerging exascale computing on nucleic acid simulations, emphasizing the need for advanced computational strategies to fully exploit this technological frontier. Specifically, we introduce recent breakthroughs in computer architectures for large-scale biomolecular simulations and review the simulation protocols for nucleic acids regarding force fields, enhanced sampling methods, coarse-grained models, and interactions with ligands. We also explore the integration of machine learning methods into simulations, which promises to significantly enhance the predictive modeling of biomolecules and the analysis of complex data generated by the exascale simulations. Finally, we discuss the challenges and perspectives for biomolecular simulations as we enter the dawning exascale computing era.
The Trans-Activator Receptor (TAR) RNA, located at the 5'-end untranslated region (5' UTR) of the human immunodeficiency virus type 1 (HIV-1), is pivotal in the virus's life cycle. As the initial functional domain, it folds during the transcription of viral mRNA. Although TAR's role in recruiting the Tat protein for trans-activation is established, the detailed kinetic mechanisms at play during early transcription, especially at points of temporary transcriptional pausing, remain elusive. Moreover, the precise physical processes of transcriptional pause and subsequent escape are not fully elucidated. This study focuses on the folding kinetics of TAR and the biological implications by integrating computer simulations of RNA folding during transcription with nuclear magnetic resonance (NMR) spectroscopy data. The findings reveal insights into the folding mechanism of a non-native intermediate that triggers transcriptional pause, along with different folding pathways leading to transcriptional pause and readthrough. The profiling of the cotranscriptional folding pathway and identification of kinetic structural intermediates reveal a novel mechanism for viral transcriptional regulation, which could pave the way for new antiviral drug designs targeting kinetic cotranscriptional folding pathways in viral RNAs.
The placenta plays a crucial role in successful mammalian reproduction. Ruminant animals possess a semi-invasive placenta characterized by a highly vascularized structure formed by maternal endometrial caruncles and fetal placental cotyledons, essential for full-term fetal development. The cow placenta harbors at least two trophoblast cell populations: uninucleate (UNC) and binucleate (BNC) cells. However, the limited capacity to elucidate the transcriptomic dynamics of the placental natural environment has resulted in a poor understanding of both the molecular and cellular interactions between trophoblast cells and niches, and the molecular mechanisms governing trophoblast differentiation and functionalization. To fill this knowledge gap, we employed Stereo-seq to map spatial gene expression patterns at near single-cell resolution in the cow placenta at 90 and 130 days of gestation, attaining high-resolution, spatially resolved gene expression profiles. Based on clustering and cell marker gene expression analyses, key transcription factors, including YBX1 and NPAS2, were shown to regulate the heterogeneity of trophoblast cell subpopulations. Cell communication and trajectory analysis provided a framework for understanding cell-cell interactions and the differentiation of trophoblasts into BNCs in the placental microenvironment. Differential analysis of cell trajectories identified a set of genes involved in regulation of trophoblast differentiation. Additionally, spatial modules and co-variant genes that help shape specific tissue structures were identified. Together, these findings provide foundational insights into important biological pathways critical to the placental development and function in cows.
Gene Expression Profiling , Placenta , Placentation , Transcriptome , Animals , Cattle/genetics , Female , Pregnancy , Placenta/metabolism , Trophoblasts/metabolism
For metastatic prostate cancer, androgen deprivation therapy (ADT) is the key strategy to control the disease. However, after 18-24 months of treatment, most patients will progress from metastatic hormone-sensitive prostate cancer (mHSPC) to metastatic castration-resistant prostate cancer (mCRPC) even with ADT. Once patients enter into mCRPC, they face with significant declines in quality of life and a dramatically reduced survival period. Thus, doublet therapy, which combines ADT with new hormone therapy (NHT) or ADT with docetaxel chemotherapy, substitutes ADT alone and has become the "gold standard" for the treatment of mHSPC. In recent years, triplet therapy, which combines ADT with NHT and docetaxel chemotherapy, has also achieved impressive effects in mHSPC. This article provides a comprehensive review of the recent applications of the triplet therapy in the field of mHSPC.
ETHNOPHARMACOLOGICAL RELEVANCE: Berberine (BBR) is the main active component from Coptidis rhizome, a well-known Chinese herbal medicine used for metabolic diseases, especially diabetes for thousands of years. BBR has been reported to cure various metabolic disorders, such as nonalcoholic fatty liver disease (NAFLD). However, the direct proteomic targets and underlying molecular mechanism of BBR against NAFLD remain less understood. AIM OF THE STUDY: To investigate the direct target and corresponding molecular mechanism of BBR on NAFLD is the aim of the current study. MATERIALS AND METHODS: High-fat diet (HFD)-fed mice and oleic acid (OA) stimulated HepG2 cells were utilized to verify the beneficial impacts of BBR on glycolipid metabolism profiles. The click chemistry in proteomics, DARTS, CETSA, SPR and fluorescence co-localization analysis were conducted to identify the targets of BBR for NAFLD. RNA-seq and shRNA/siRNA were used to investigate the downstream pathways of the target. RESULTS: BBR improved hepatic steatosis, ameliorated insulin resistance, and reduced TG levels in the NAFLD models. Importantly, Aldo-keto reductase 1B10 (AKR1B10) was first proved as the target of BBR for NAFLD. The gene expression of AKR1B10 increased significantly in the NAFLD patients' liver tissue. We further demonstrated that HFD and OA increased AKR1B10 expression in the C57BL/6 mice's liver and HepG2 cells, respectively, whereas BBR decreased the expression and activities of AKR1B10. Moreover, the knockdown of AKR1B10 by applying shRNA/siRNA profoundly impacted the beneficial effects on the pathogenesis of NAFLD by BBR. Meanwhile, the changes in various proteins (ACC1, CPT-1, GLUT2, etc.) are responsible for hepatic lipogenesis, fatty acid oxidation, glucose uptake, etc. by BBR were reversed by the knockdown of AKR1B10. Additionally, RNA-seq was used to identify the downstream pathway of AKR1B10 by examining the gene expression of liver tissues from HFD-fed mice. Our findings revealed that BBR markedly increased the protein levels of PPARα while downregulating the expression of PPARγ. However, various proteins of PPAR signaling pathways remained unaffected post the knockdown of AKR1B10. CONCLUSIONS: BBR alleviated NAFLD via mediating PPAR signaling pathways through targeting AKR1B10. This study proved that AKR1B10 is a novel target of BBR for NAFLD treatment and helps to find new targets for the treatment of NAFLD by using active natural compounds isolated from traditional herbal medicines as the probe.
Background: A variety of symptoms, particularly cognitive, psychiatric and neurological symptoms, may persist for a long time among individuals recovering from COVID-19. However, the underlying mechanism of these brain abnormalities remains unclear. This study aimed to investigate the long-term neuroimaging effects of COVID-19 infection on brain functional activities using resting-state functional magnetic resonance imaging (rs-fMRI). Methods: Fifty-two survivors 27 months after infection (mild-moderate group: 25 participants, severe-critical: 27 participants), from our previous community participants, along with 35 healthy controls, were recruited to undergo fMRI scans and comprehensive cognitive function measurements. Participants were evaluated by subjective assessment of Cognitive Failures Questionnaire-14 (CFQ-14) and Fatigue Scale-14 (FS-14), and objective assessment of Montreal Cognitive Assessment (MoCA), N-back, and Simple Reaction Time (SRT). Each had rs-fMRI at 3T. Measures such as the amplitude of low-frequency fluctuation (ALFF), fractional amplitude of low-frequency fluctuations (fALFF), and regional homogeneity (ReHo) were calculated. Findings: Compared with healthy controls, survivors of mild-moderate acute symptoms group and severe-critical group had a significantly higher score of cognitive complains involving cognitive failure and mental fatigue. However, there was no difference of cognitive complaints between two groups of COVID-19 survivors. The performance of three groups was similar on the score of MoCA, N-back and SRT. The rs-fMRI results showed that COVID-19 survivors exhibited significantly increased ALFF values in the left putamen (PUT.L), right inferior temporal gyrus (ITG.R) and right pallidum (PAL.R), while decreased ALFF values were observed in the right superior parietal gyrus (SPG.R) and left superior temporal gyrus (STG.L). Additionally, decreased ReHo values in the right precentral gyrus (PreCG.R), left postcentral gyrus (PoCG.L), left calcarine fissure and surrounding cortex (CAL.L) and left superior temporal gyrus (STG.L). Furthermore, significant negative correlations between the ReHo values in the STG.L, and CFQ-14 and mental fatigue were found. Interpretation: This long-term study suggests that individuals recovering from COVID-19 continue to experience cognitive complaints, psychiatric and neurological symptoms, and brain functional alteration. The rs-fMRI results indicated that the changes in brain function in regions such as the putamen, temporal lobe, and superior parietal gyrus may contribute to cognitive complaints in individuals with long COVID even after 2-year infection. Funding: The National Programs for Brain Science and Brain-like Intelligence Technology of China, the National Natural Science Foundation of China, Natural Science Foundation of Beijing Municipality of China, and the National Key Research and Development Program of China.
The distribution of polycyclic aromatic hydrocarbons (PAHs) in the ocean is affected by the sorption-desorption process of sediment particles. This process is determined by the concentration of PAHs in seawater, water temperature, and organic matter content of sediment particles. Quantitative relationships between the net sorption rates (=the difference of sorption and desorption rates) and these factors have not been established yet and used in PAH transport models. In this study, phenanthrene was chosen as the representative of PAHs. Three groups of experimental data were collected to address the dependence of the net sorption processes on the initial concentration, water temperature, and organic carbon content representing organic matter content. One-site and two-compartment mass-transfer models were tested to represent the experimental data using various parameters. The results showed that the two-compartment mass-transfer model performed better than the one-site mass-transfer model. The parameters of the two-compartment mass-transfer model include the sorption rate coefficients kafand kas (L g-1 min-1), and the desorption rate coefficients kdf and kds (min-1). The parameters at different temperatures and organic carbon contents were obtained by numerical simulations. Linear relationships were obtained between the parameters and water temperature, as well as organic carbon content. kaf, kas and kdf decreased linearly, while kds increased linearly with temperature. kaf, kas and kdf increased linearly, while kds decreased linearly with organic carbon content. The r2 values between the simulation results based on the relationships and the experimental results reached 0.96-0.99, which supports the application of the model to simulate sorption-desorption processes at different water temperatures and organic carbon contents in a realistic ocean.
Geologic Sediments , Phenanthrenes , Seawater , Temperature , Water Pollutants, Chemical , Phenanthrenes/chemistry , Geologic Sediments/chemistry , Adsorption , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/chemistry , Seawater/chemistry , Environmental Monitoring/methods , Models, Theoretical , Models, Chemical
