Identification of circRNAs expression profiles and functional networks in parotid gland of type 2 diabetes mouse.

BACKGROUND: Circular RNAs (circRNAs) are a novel kind of non-coding RNAs proved to play crucial roles in the development of multiple diabetic complications. However, their expression and function in diabetes mellitus (DM)-impaired salivary glands are unknown. RESULTS: By using microarray technology, 663 upregulated and 999 downregulated circRNAs companied with 813 upregulated and 525 downregulated mRNAs were identified in the parotid glands (PGs) of type2 DM mice under a 2-fold change and P < 0.05 cutoff criteria. Gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) analysis of upregulated mRNAs showed enrichments in immune system process and peroxisome proliferator-activated receptor (PPAR) signaling pathway. Infiltration of inflammatory cells and increased inflammatory cytokines were observed in diabetic PGs. Seven differently expressed circRNAs validated by qRT-PCR were selected for coding-non-coding gene co-expression (CNC) and competing endogenous RNA (ceRNA) networks analysis. PPAR signaling pathway was primarily enriched through analysis of circRNA-mRNA networks. Moreover, the circRNA-miRNA-mRNA networks highlighted an enrichment in the regulation of actin cytoskeleton. CONCLUSION: The inflammatory response is elevated in diabetic PGs. The selected seven distinct circRNAs may attribute to the injury of diabetic PG by modulating inflammatory response through PPAR signaling pathway and actin cytoskeleton in diabetic PGs.

Integrating UPLC-QTOF-MS/MS and UPLC-DAD to evaluate the influence of sulfur-fumigated Paeoniae Radix Alba on the overall quality of three Si-Wu-Tang formulations.

INTRODUCTION: Sulfur-fumigation of Paeoniae Radix Alba (PRA) could induce the chemical transformation of its bioactive component paeoniflorin into a sulfur-containing derivative paeoniflorin sulfite, and thus alter the quality, bioactivities, pharmacokinetics, and toxicities of PRA. However, how sulfur-fumigated PRA (S-PRA) affects the quality of PRA-containing complex preparations has not been intensively evaluated. OBJECTIVES: We intend to evaluate the influence of S-PRA on the overall quality of three kinds of Si-Wu-Tang (SWT) formulations, i.e., decoction (SWT-D), granule (SWT-G), and mixture (SWT-M). MATERIAL AND METHODS: An UPLC-DAD multi-components quantification method was used to compare the transfer rates of paeoniflorin sulfite and other 10 bioactive components between S-PRA-containing and NS-PRA-containing SWT formulations. An UPLC-QTOF-MS/MS-based target metabolomics approach was applied to explore the differential sulfur-containing derivatives in S-PRA-containing SWT formulations. RESULTS: The transfer rates of paeoniflorin sulfite in three S-PRA-containing SWT formulations were all higher than 100%. Moreover, S-PRA also increased the transfer rate of 5-hydroxymethylfurfural, 1,2,3,4,6-O-pentagalloylglucose, whereas decreased that of paeoniflorin, albiflorin, and ferulic acid in three SWT formulations. Six pinane monoterpene glucoside sulfites originally identified in S-PRA, were also detectable in three S-PRA-containing SWT formulations. In addition, seven phenolic acid sulfites including (3Z)-6-sulfite-ligustilide, (3E)-6-sulfite-ligustilide, 6,8-disulfite-ligustilide, ferulic acid sulfite, neochlorogenic acid sulfite, chlorogenic acid sulfite, and angelicide sulfite (or isomer) were newly identified in these three S-PRA-containing formulations. CONCLUSION: S-PRA could differentially affect the transfer rate of paeoniflorin sulfite and other bioactive components during the preparation of three SWT formulations and subsequently the overall quality thereof.

Accuracy of brain natriuretic peptide and N-terminal brain natriuretic peptide for detecting paediatric pulmonary hypertension: a systematic review and meta-analysis.

OBJECTIVE: Pulmonary hypertension (PH) is a life-threatening disease, especially in paediatric population. Symptoms of paediatric PH are non-specific. Accurate detection of paediatric PH is helpful for early treatment and mortality reduction. Therefore, we assessed the overall performance of brain natriuretic peptide (BNP) and N-terminal brain natriuretic peptide (NT-proBNP) for diagnosing PH in paediatric population. METHODS: PubMed, Web of Science, Cochrane Library and Embase databases were screened since their respective inceptions until August 2023. A bivariate random model and a hierarchical summary receiver operating characteristic model were used together to evaluate and summarize the overall performance of BNP and NT-proBNP for diagnosing paediatric PH. RESULTS: Eighteen studies using BNP/NT-proBNP were assessed, comprising 1127 samples. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and area under the curve (AUROC) of BNP/NT-proBNP were separately as 0.81, 0.87, 6.33, 0.21, 29.50 and 0.91, suggesting a good diagnostic performance of BNP/NT-proBNP for detecting PH in paediatric population. For BNP, the pooled sensitivity, specificity, PLR, NLR, DOR and AUROC were 0.83, 0.89, 7.76, 0.19, 40.90 and 0.93, indicating the diagnostic accuracy of BNP for paediatric PH patients was good. For NT-proBNP, the pooled sensitivity, specificity, PLR, NLR, DOR and AUROC were 0.81, 0.86, 5.59, 0.22, 24.96 and 0.90, showing that NT-proBNP could provide a good value for detecting paediatric PH. CONCLUSIONS: Both BNP and NT-proBNP are good markers for differentiating paediatric PH patients from non-PH individuals.

Accurate detection of paediatric PH is helpful for early treatment and mortality reduction. This study shows that both BNP and NT-proBNP are good markers for detecting paediatric PH. In clinical practice, we recommend that BNP and NT-proBNP are auxiliary biomarkers in diagnosing paediatric PH.

Molecular and biological characterization of a bunyavirus infecting the brown planthopper (Nilaparvata lugens).

A negative-strand symbiotic RNA virus, tentatively named Nilaparvata lugens Bunyavirus (NLBV), was identified in the brown planthopper (BPH, Nilaparvata lugens). Phylogenetic analysis indicated that NLBV is a member of the genus Mobuvirus (family Phenuiviridae, order Bunyavirales). Analysis of virus-derived small interfering RNA suggested that antiviral immunity of BPH was successfully activated by NLBV infection. Tissue-specific investigation showed that NLBV was mainly accumulated in the fat-body of BPH adults. Moreover, NLBV was detected in eggs of viruliferous female BPHs, suggesting the possibility of vertical transmission of NLBV in BPH. Additionally, no significant differences were observed for the biological properties between NLBV-infected and NLBV-free BPHs. Finally, analysis of geographic distribution indicated that NLBV may be prevalent in Southeast Asia. This study provided a comprehensive characterization on the molecular and biological properties of a symbiotic virus in BPH, which will contribute to our understanding of the increasingly discovered RNA viruses in insects.

Maintenance of persistent transmission of a plant arbovirus in its insect vector mediated by the Toll-Dorsal immune pathway.

Throughout evolution, arboviruses have developed various strategies to counteract the host's innate immune defenses to maintain persistent transmission. Recent studies have shown that, in addition to bacteria and fungi, the innate Toll-Dorsal immune system also plays an essential role in preventing viral infections in invertebrates. However, whether the classical Toll immune pathway is involved in maintaining the homeostatic process to ensure the persistent and propagative transmission of arboviruses in insect vectors remain unclear. In this study, we revealed that the transcription factor Dorsal is actively involved in the antiviral defense of an insect vector (Laodelphax striatellus) by regulating the target gene, zinc finger protein 708 (LsZN708), which mediates downstream immune-related effectors against infection with the plant virus (Rice stripe virus, RSV). In contrast, an antidefense strategy involving the use of the nonstructural-protein (NS4) to antagonize host antiviral defense through competitive binding to Dorsal from the MSK2 kinase was employed by RSV; this competitive binding inhibited Dorsal phosphorylation and reduced the antiviral response of the host insect. Our study revealed the molecular mechanism through which Toll-Dorsal-ZN708 mediates the maintenance of an arbovirus homeostasis in insect vectors. Specifically, ZN708 is a newly documented zinc finger protein targeted by Dorsal that mediates the downstream antiviral response. This study will contribute to our understanding of the successful transmission and spread of arboviruses in plant or invertebrate hosts.

Effect of modifying pumpkin preparation on oral processing of breads.

There is an increasing demand for texture sensations of bread during mastication, with reformulation being needed. This study investigated how bread structure influences oral processing behavior and texture perception. Variations in bread structure were created by manipulating ingredient additions, including pumpkin content and pumpkin processing methods. Results indicated that the physical, chemical, and structural properties drove the oral processing behaviors, and texture sensations were highly correlated with bolus properties. At the beginning and middle of the mastication, bolus from breads with low pumpkin-content required more saliva and exhibited greater hardness, lower adhesiveness, and a higher proportion of small-piece particles than the bolus from high pumpkin-content breads. Bolus from pumpkin pulp breads required more saliva, and was softer, stickier, and generated particles with a lower degree of degradation than the bolus from pumpkin puree breads. However, at the end period, the bolus properties tended to change to similar values. Low pumpkin content breads were initially perceived chewy, whereas high pumpkin content, soft. The dominance rate for soft sensation was higher and lasted longer in breads with pumpkin puree than in breads with pumpkin pulp. Finally, six bread samples were all perceived as hydrated, sticky, and crumbly. This study contributes to a better understanding of the impact of reformulation on oral behavior and sensory properties.

HSPA12A maintains aerobic glycolytic homeostasis and Histone3 lactylation in cardiomyocytes to attenuate myocardial ischemia/reperfusion injury.

Myocardial ischemia/reperfusion (MI/R) injury is a major cause of adverse outcomes of revascularization following myocardial infarction. Anaerobic glycolysis during myocardial ischemia is well studied, but the role of aerobic glycolysis during the early phase of reperfusion is incompletely understood. Lactylation of Histone H3 (H3) is an epigenetic indicator of the glycolytic switch. Heat shock protein A12A (HSPA12A) is an atypic member of the HSP70 family. In the present study, we report that, during reperfusion following myocardial ischemia, HSPA12A was downregulated and aerobic glycolytic flux was decreased in cardiomyocytes. Notably, HSPA12A KO in mice exacerbated MI/R-induced aerobic glycolysis decrease, cardiomyocyte death, and cardiac dysfunction. Gain- and loss-of-function studies demonstrated that HSPA12A was required to support cardiomyocyte survival upon hypoxia/reoxygenation (H/R) challenge and that its protective effects were mediated by maintaining aerobic glycolytic homeostasis for H3 lactylation. Further analyses revealed that HSPA12A increased Smurf1-mediated Hif1α protein stability, thus increasing glycolytic gene expression to maintain appropriate aerobic glycolytic activity to sustain H3 lactylation during reperfusion and, ultimately, improving cardiomyocyte survival to attenuate MI/R injury.

Preparation and Oil Adsorption of Cellulose-graft-poly(butyl acrylate-N,N'-methylene Bisacrylamide).

With the advancement of industrial economies, incidents involving spills of petroleum products have become increasingly frequent. The resulting pollutants pose significant threats to air, water, soil, plant and animal survival, as well as human health. In this study, microcrystalline cellulose served as the matrix and benzoyl peroxide (BPO) as the initiator, while butyl acrylate (BA) and N,N'-methylene bisacrylamide (MBA) were employed as graft monomers. Through free radical graft polymerization, cellulose-graft-poly(butyl acrylate-N,N'-methylene bisacrylamide) [Cell-g-P(BA-MBA)], possessing oil-adsorbing properties, was synthesized. The chemical structure, elemental composition, surface morphology and wetting properties of the graft polymerization products have been characterized, using infrared spectroscopy, elemental analysis, scanning electron microscopy and contact angle testing. The adsorption properties of Cell-g-P(BA-MBA) for various organic solvents and oils were then assessed. The experimental results demonstrated that Cell-g-P(BA-MBA) exhibited a maximum adsorption capacity of 37.55 g/g for trichloromethane. Adsorption kinetics experiments indicated a spontaneous and exothermic process involving physical adsorption, conforming to the Freundlich isotherm model. Furthermore, adsorption kinetics experiments revealed that Cell-g-P(BA-MBA) displayed favorable reuse and regeneration performance, maintaining its adsorption capacity essentially unchanged over fifteen adsorption-desorption cycles.

HSPA12A acts as a scaffolding protein to inhibit cardiac fibroblast activation and cardiac fibrosis.

INTRODUCTION: Cardiac fibrosis is the main driver for adverse remodeling and progressive functional decline in nearly all types of heart disease including myocardial infarction (MI). The activation of cardiac fibroblasts (CF) into myofibroblasts is responsible for cardiac fibrosis. Unfortunately, no ideal approach for controlling CF activation currently exists. OBJECTIVES: This study investigated the role of Heat shock protein A12A (HSPA12A), an atypical member of the HSP70 family, in CF activation and MI-induced cardiac fibrosis. METHODS: Primary CF and Hspa12a knockout mice were used in the experiments. CF activation was indicated by the upregulation of myofibroblast characters including alpha-Smooth muscle actin (αSMA), Collagen, and Fibronectin. Cardiac fibrosis was illustrated by Masson's trichrome and picrosirius staining. Cardiac function was examined using echocardiography. Glycolytic activity was indicated by levels of extracellular lactate and the related protein expression. Protein stability was examined following cycloheximide and MG132 treatment. Protein-protein interaction was examined by immunoprecipitation-immunoblotting analysis. RESULTS: HSPA12A displayed a high expression level in quiescent CF but showed a decreased expression in activated CF, while ablation of HSPA12A in mice promoted CF activation and cardiac fibrosis following MI. HSPA12A overexpression inhibited the activation of primary CF through inhibiting glycolysis, while HSPA12A knockdown showed the opposite effects. Moreover, HSPA12A upregulated the protein expression of transcription factor p53, by which mediated the HSPA12A-induced inhibition of glycolysis and CF activation. Mechanistically, this action of HSPA12A was achieved by acting as a scaffolding protein to bind p53 and ubiquitin specific protease 10 (USP10), thereby promoting the USP10-mediated p53 protein stability and the p53-medicated glycolysis inhibition. CONCLUSION: The present study provided clear evidence that HSPA12A is a novel endogenous inhibitor of CF activation and cardiac fibrosis. Targeting HSPA12A in CF could represent a promising strategy for the management of cardiac fibrosis in patients.

Watching (De)Intercalation of 2D Metals in Epitaxial Graphene: Insight into the Role of Defects.

Intercalation forms heterostructures, and over 25 elements and compounds are intercalated into graphene, but the mechanism for this process is not well understood. Here, the de-intercalation of 2D Ag and Ga metals sandwiched between bilayer graphene and SiC are followed using photoemission electron microscopy (PEEM) and atomistic-scale reactive molecular dynamics simulations. By PEEM, de-intercalation "windows" (or defects) are observed in both systems, but the processes follow distinctly different dynamics. Reversible de- and re-intercalation of Ag is observed through a circular defect where the intercalation velocity front is 0.5 nm s-1 ± 0.2 nm s.-1 In contrast, the de-intercalation of Ga is irreversible with faster kinetics that are influenced by the non-circular shape of the defect. Molecular dynamics simulations support these pronounced differences and complexities between the two Ag and Ga systems. In the de-intercalating Ga model, Ga atoms first pile up between graphene layers until ultimately moving to the graphene surface. The simulations, supported by density functional theory, indicate that the Ga atoms exhibit larger binding strength to graphene, which agrees with the faster and irreversible diffusion kinetics observed. Thus, both the thermophysical properties of the metal intercalant and its interaction with defective graphene play a key role in intercalation.

Shuangshi Tonglin Capsule treats benign prostatic hyperplasia through the ROS/NLRP3 signaling pathway.

OBJECTIVE: To explore the effects of the SSTL on BPH and clarify the therapeutic mechanisms. METHODS: Animal model of BPH was established by castration and subcutaneous injection of TP into SD rats; rats were orally administered SSTL for 28 days while modeling. Detection of PI, LI and RI in rats, to observe histopathological changes and collagen deposition in the prostate tissue. Detects levels of sex hormones and inflammatory factors in serum and tissues of rats, the test kit detects levels of lipid peroxides and antioxidants in serum and tissues. Fluorescent staining analysis of tissue ROS; the expression of NLRP3 inflammatory vesicles was observed by immunohistochemistry; Western blotting detected the expression of NOX4, NOX2, NLRP3 inflammatory vesicles, ASC, Cleaved Caspase-1, Caspase-1, IL-1ß. RESULTS: After SSTL capsule treatment, the PI and RI of the rats decrease. HE and Masson staining showed that SSTL ameliorated the pathological damage and reduced collagen deposition in the prostate tissue of BPH rats; ELISA results showed that SSTL was able to reduce T, DHT, TNF-α, IL-1ß levels in BPH rats. The test kit showed that SSTL made the levels of MDA, CAT and GSH-Px in the serum and prostate tissue of rats and increased the activity of SOD. The results of ROS fluorescence showed that the ROS level was reduced in SSTL group; Western blotting showed that SSTL could cause down-regulation of NOX4, NOX2, NLRP3, ASC, Cleaved Caspase-1, IL-1ß protein expression. CONCLUSION: SSTL can reduce the PI and RI in BPH rats, it can also inhibit the level of sex hormones and inflammatory factors in BPH rats, which thereby reducing the histopathological damage of prostate gland in BPH rats, and can treat BPH in rats through ROS/NLRP3 pathway.

Murine trophoblast organoids as a model for trophoblast development and CRISPR-Cas9 screening.

The placenta becomes one of the most diversified organs during placental mammal radiation. The main in vitro model for studying mouse trophoblast development is the 2D differentiation model of trophoblast stem cells, which is highly skewed to certain lineages and thus hampers systematic screens. Here, we established culture conditions for the establishment, maintenance, and differentiation of murine trophoblast organoids. Murine trophoblast organoids under the maintenance condition contain stem cell-like populations, whereas differentiated organoids possess various trophoblasts resembling placental ones in vivo. Ablation of Nubpl or Gcm1 in trophoblast organoids recapitulated their deficiency phenotypes in vivo, suggesting that those organoids are valid in vitro models for trophoblast development. Importantly, we performed an efficient CRISPR-Cas9 screening in mouse trophoblast organoids using a focused sgRNA (single guide RNA) library targeting G protein-coupled receptors. Together, our results establish an organoid model to investigate mouse trophoblast development and a practicable approach to performing forward screening in trophoblast lineages.

Shuangshi Tonglin capsule improves chronic prostatitis through the SIRT-1/AMPK and MAPK signalling pathways.

Objectives: To explore the effects of the Shuangshi Tonglin (SSTL) capsule on CP/CPPS and reveal the therapeutic mechanisms. Methods: A CP/CPPS rat-model group received an intraprostatic injection of CFA. SSTL capsule were administered daily by oral gavage at doses of 1.25, 2.5, and 5.0 g/kg for 28 days. Pain threshold tests were performed, and prostate and blood samples were collected. We performed histological analysis of the prostate tissue and immunohistochemical analysis of TNF-α and COX-2. Measure the TNF-α levels, detect antioxidant levels in serum and prostate tissue, and evaluate the expression of proteins with the AMPK/SIRT-1 and MAPK signalling pathways. Results: After SSTL capsule treatment, all animals exhibited an increased mechanical pain threshold in the lower abdomen, decreased inflammation in the stroma, and reduced histological structural damage. Inflammation was reduced through the observed decrease in the levels of various inflammatory factors, as well as in the increase of the levels of MDA, p-AMPK, and SIRT-1. The suppression of IKKß, p-P38, p-ERK and p-JNK was also observed. Conclusions: SSTL capsule treatment decreased inflammation in the stroma and reduced histological structural damage. It improved CP/CPPS symptoms by inhibiting oxidative stress and inflammation. Our study indicates that the SSTL capsule is an effective treatment for prostatitis.

Co-option of a non-retroviral endogenous viral element in planthoppers.

Non-retroviral endogenous viral elements (nrEVEs) are widely dispersed throughout the genomes of eukaryotes. Although nrEVEs are known to be involved in host antiviral immunity, it remains an open question whether they can be domesticated as functional proteins to serve cellular innovations in arthropods. In this study, we found that endogenous toti-like viral elements (ToEVEs) are ubiquitously integrated into the genomes of three planthopper species, with highly variable distributions and polymorphism levels in planthopper populations. Three ToEVEs display exon‒intron structures and active transcription, suggesting that they might have been domesticated by planthoppers. CRISPR/Cas9 experiments revealed that one ToEVE in Nilaparvata lugens, NlToEVE14, has been co-opted by its host and plays essential roles in planthopper development and fecundity. Large-scale analysis of ToEVEs in arthropod genomes indicated that the number of arthropod nrEVEs is currently underestimated and that they may contribute to the functional diversity of arthropod genes.

Predicting Respiratory Rate from Electrocardiogram and Photoplethysmogram Using a Transformer-Based Model.

The respiratory rate (RR) serves as a critical physiological parameter in the context of both diagnostic and prognostic evaluations. Due to the challenges of direct measurement, RR is still predominantly measured through the traditional manual counting-breaths method in clinic practice. Numerous algorithms and machine learning models have been developed to predict RR using physiological signals, such as electrocardiogram (ECG) or/and photoplethysmogram (PPG) signals. Yet, the accuracy of these existing methods on available datasets remains limited, and their prediction on new data is also unsatisfactory for actual clinical applications. In this paper, we proposed an enhanced Transformer model with inception blocks for predicting RR based on both ECG and PPG signals. To evaluate the generalization capability on new data, our model was trained and tested using subject-level ten-fold cross-validation using data from both BIDMC and CapnoBase datasets. On the test set, our model achieved superior performance over five popular deep-learning-based methods with mean absolute error (1.2) decreased by 36.5% and correlation coefficient (0.85) increased by 84.8% compared to the best results of these models. In addition, we also proposed a new pipeline to preprocess ECG and PPG signals to improve model performance. We believe that the development of the TransRR model is expected to further expedite the clinical implementation of automatic RR estimation.

Low Ni and Co olivine in Chang'E-5 basalts reveals the origin of the young volcanism on the Moon.

Mare basalts returned by the Chang'E-5 (CE5) mission extend the duration of lunar volcanism almost one billion years longer than previously dated. Recent studies demonstrated that the young volcanism was related neither to radiogenic heating nor to hydrous melting. These findings beg the question of how the young lunar volcanism happened. Here we perform high-precision minor element analyses of olivine in the CE5 basalts, focusing on Ni and Co. Our results reveal that the CE5 basalt olivines have overall lower Ni and Co than those in the Apollo low-Ti basalts. The distinctive olivine chemistry with recently reported bulk-rock chemistry carries evidence for more late-stage clinopyroxene-ilmenite cumulates of the lunar magma ocean (LMO) in the CE5 mantle source. The involvement of these Fe-rich cumulates could lower the mantle melting temperature and produce low MgO magma, inhibiting Ni and Co partitioning into the magma during lunar mantle melting and forming low Ni and Co olivines for the CE5 basalts. Moreover, the CE5 olivines show a continuous decrease of Ni and Co with crystallization proceeding. Fractional crystallization modeling indicates that Co decreasing with crystallization resulted from CaO and TiO2 enrichment (with MgO and SiO2 depletion) in the CE5 primary magma. This further supports the significant contribution of late-stage LMO cumulates to the CE5 volcanic formation. We suggest that adding easily melted LMO components resulting in mantle melting point depression is a key pathway for driving prolonged lunar volcanism. This study highlights the usefulness of olivine for investigating magmatic processes on the Moon.

High-Resolution Cathodoluminescence Images of Igneous and Metamorphic Monazite.

Monazite is one of the most important dating accessory minerals for deciphering geological processes. The growth history of monazite can be identified by its internal structure; thus, high-resolution imaging is necessary for in situ U-Th-Pb dating. In this study, cathodoluminescence (CL) techniques were optimized via the key parameters of working distance, accelerating voltage, and beam current and were then applied to monazites from igneous and metamorphic rocks. The CL images of igneous monazites show concentric oscillatory zoning, whereas those of metamorphic monazites clearly show homogeneous, patchy, or core-rim structures. CL imaging is a more effective approach than back-scattered electron (BSE) imaging for the observation of the internal structure of monazite and may yield additional information. CL can add to the interpretation of X-ray maps and the two techniques that may complement each other. The CL spectra of monazite consist of broad peaks and sets of narrow emission rare earth element 3+ (REE3+) peaks (Gd3+, Tb3+, Dy3+, and Sm3+). The microstructures observed via CL imaging techniques can show a certain relationship between light REE (LREE) and U, Th, and Si in some igneous monazites and heavy REE (HREE) variation in some metamorphic monazites.

Joint Theoretical and Experimental Study of Stress Graphitization in Aligned Carbon Nanotube/Carbon Matrix Composites.

Stress graphitization is a unique phenomenon at the carbon nanotube (CNT)-matrix interfaces in CNT/carbon matrix (CNT/C) composites. A lack of fundamental atomistic understanding of its evolution mechanisms and a gap between the theoretical and experimental research have hindered the pursuit of utilizing this phenomenon for producing ultrahigh-performance CNT/C composites. Here, we performed reactive molecular dynamics simulations along with an experimental study to explore stress graphitization mechanisms of a CNT/polyacrylonitrile (PAN)-based carbon matrix composite. Different CNT contents in the composite were considered, while the nanotube alignment was controlled in one direction in the simulations. We observe that the system with a higher CNT content exhibits higher localized stress concentration in the periphery of CNTs, causing alignment of the nitrile groups in the PAN matrix along the CNTs, which subsequently results in preferential dehydrogenation and clustering of carbon rings and eventually graphitization of the PAN matrix when carbonized at 1500 K. These simulation results have been validated by experimentally produced CNT/PAN-based carbon matrix composite films, with transmission electron microscopy images showing the formation of additional graphitic layers converted by the PAN matrix around CNTs, where 82 and 144% improvements of the tensile strength and Young's modulus are achieved, respectively. The presented atomistic details of stress graphitization can provide guidance for further optimizing CNT-matrix interfaces in a more predictive and controllable way for the development of novel CNT/C composites with high performance.

UPLC-QTOF-MS/MS assisted UPLC-TQ-MS/MS strategy to comparatively investigate the rat pharmacokinetics of N-acetyldopamine oligomers derived from Cicadae Periostracum.

Cicadae Periostracum (CP), the slough molted from the nymph of Cryptotympana pustulata, is a widely used medicinal material in traditional Chinese medicine (TCM). N-acetyldopamine oligomers (NAOs), the homologues of acetyldopamine, including N-acetyldopamine dimers/trimers/tetramers/pentamers (NADs/NATrs/NATes/NAPs), side-chain isomer of dimers/trimers (SCIDs/SCITrs), are major bioactive ingredients of CP. However, owing to commercially unavailable reference substances of all NAOs, simultaneous quantification of these NAOs in biological samples is difficult, and thus their pharmacokinetics are still unknown. In this study, a comprehensive strategy for simultaneous quantification/semi-quantification of NAOs in plasma with single N-acetyldopamine dimer A (NAD-A) as reference substance was established and comparatively investigated their pharmacokinetics after oral administration of pure NAD-A and two types of CP extracts, i.e., post-molting-washed slough (CP-WAT) and pre-molting-washed slough (CP-WBT). A UPLC-QTOF-MS/MS assisted UPLC-TQ-MS/MS strategy was developed to quantify NAOs in rat plasma. NAOs in CP extract were qualitatively characterized by UPLC-QTOF-MS/MS, then the quasi-molecular ions and characteristic fragment ions of the identified NAOs by UPLC-QTOF-MS/MS were transferred to UPLC-TQ-MS/MS as parent-daughter ion pairs for MRM mode quantification of the NAOs, and the method was validated with single NAD-A for quantifying NAD-A and semi-quantifying other NAOs in plasma. The established method was applied to compare the pharmacokinetics of NAOs after oral administration of NAD-A and the extracts of CP-WBT/CP-WAT respectively. Six quasi-molecular ions and characteristic fragment ion m/z 192.1 were characterized by UPLC-QTOF-MS/MS and transferred to be the parent-daughter ion pairs for UPLC-TQ-MS/MS analysis of six kinds of NAOs. For the pharmacokinetics, NAD-A showed double peaks absorption character when administered with single compound, but with higher relative bioavailability when administered with CP extracts with the similar dosage. Compared with CP-WAT, NAOs in CP-WBT reached the maximum plasma concentration in much shorter time.

Pyrolysis and oxidation of benzene and cyclopentadiene by NOx: a ReaxFF molecular dynamics study.

Benzene (C6H6) and 1,3-cyclopentadiene (c-C5H6) are critical intermediate species in the combustion of fossil fuel and the formation of polycyclic aromatic hydrocarbons (PAHs). This study investigates the underlying mechanisms of pyrolysis and oxidation of C6H6 and c-C5H6 in the presence of O2, NO and NO2, respectively, under combustion conditions via ReaxFF molecular dynamics simulations. The size growth in the pyrolysis system is accompanied by an amorphous nature as well as an increase in the C/H ratio. In the oxidation sytems, NO2 is the most effective in the oxidation of both C6H6 and c-C5H6, followed by NO and O2. In the presence of NOx, O and N radicals generated in the high-temperature decomposition reactions of NO and NO2 are actively involved in the addition and H-abstraction reactions of C6H6 and c-C5H6. Remarkably, the decomposition of NO2 dramatically increases the number of O radicals in the system, which significantly accelerates the ring-opening of C6H6 and c-C5H6 by O-addition and forms linear-C6H6O and C5H6O species, respectively. Afterwards, the formation of -CH2- by H-transfer plays an essential role in the decomposition of linear-C6H6O and -C5H6O. Reaction pathways of O and N radicals with C6H6 and c-C5H6 are reported in detail. The O and N-addition of C6H6 facilitate the decomposition to resonance-stabilized cyclopentadienyl radicals after the restructuring of the C-C bond.