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1.
Front Oncol ; 14: 1254705, 2024.
Article in English | MEDLINE | ID: mdl-38601757

ABSTRACT

In the field of medical image segmentation, achieving fast and accurate semantic segmentation of tumor cell nuclei and skin lesions is of significant importance. However, the considerable variations in skin lesion forms and cell types pose challenges to attaining high network accuracy and robustness. Additionally, as network depth increases, the growing parameter size and computational complexity make practical implementation difficult. To address these issues, this paper proposes MD-UNet, a fast cell nucleus segmentation network that integrates Tokenized Multi-Layer Perceptron modules, attention mechanisms, and Inception structures. Firstly, tokenized MLP modules are employed to label and project convolutional features, reducing computational complexity. Secondly, the paper introduces Depthwise Attention blocks and Multi-layer Feature Extraction modules. The Depthwise Attention blocks eliminate irrelevant and noisy responses from coarse-scale extracted information, serving as alternatives to skip connections in the UNet architecture. The Multi-layer Feature Extraction modules capture a wider range of high-level and low-level semantic features during decoding and facilitate feature fusion. The proposed MD-UNet approach is evaluated on two datasets: the International Skin Imaging Collaboration (ISIC2018) dataset and the PanNuke dataset. The experimental results demonstrate that MD-UNet achieves the best performance on both datasets.

2.
Sci Rep ; 14(1): 9269, 2024 Apr 23.
Article in English | MEDLINE | ID: mdl-38649378

ABSTRACT

Rainwater is the main water source in arid and semiarid areas of the Loess Plateau, where rainfall is generally insufficient, ineffective and underutilized during the growing season. Thus, improving rainwater utilization efficiency is essential for sustainable agricultural development. A new system composed of rainwater harvesting, an infiltrator bucket with multiple holes and mulching (RHM), was designed to maintain soil moisture at a proper level in rain-fed orchards in arid and semiarid areas of the Loess Region of China. However, there is a lack of clarity on the effectiveness of RHM. In this study, changes in the soil environment and the growth and physiology of apricot trees were monitored via two treatments: (1) Rain-harvesting irrigation system (RHM) treatment and (2) traditional orchard treatment (CK) as a baseline. The results showed that (1) RHM could effectively improve soil water storage at depths of 0-45 cm and at a horizontal distance of 40 cm from the trunk. For the 1.4 mm light rain event, the soil water content increased by 6.3-12%, and for the two moderate rains, the soil water content increased by 12-25%. The change in the soil relative water content predicted by the LSTM model is consistent with the overall trend of the measured value and gradually decreases, and the prediction accuracy is high, with an error of 0.65. (2) The average soil temperatures at 5 cm, 20 cm and 40 cm under RHM were 17.0% (2.4 °C), 13.6% (1.9 °C) and 7.5% (1 °C) greater than those under CK, respectively. (3) Compared with the control treatment, RHM improved the growth and WUEL of apricot trees. The results highlighted the efficiency of the RHM system in enhancing the soil environment and regulating the growth and physiology of apricot trees, which has greater popularization value in arid and semiarid areas.

3.
J Invertebr Pathol ; 204: 108091, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38462166

ABSTRACT

Ameson portunus is an intracellular pathogen that infects marine crabs Portunus trituberculatus and Scylla paramamosain, causing significant economic losses. However, research into this important parasite has been limited due to the absence of an in vitro culture system. To address this challenge, we developed an in vitro cultivation model of A. portunus using RK13 cell line in this study. The fluorescent labeling assay indicated a high infection rate (∼60 %) on the first day post-infection and quantitative PCR (qPCR) detection demonstrated successful infection as early as six hours post-inoculation. Fluorescence in situ hybridization (FISH) and qPCR were used for the detection of A. portunus infected cells. The FISH probe we designed allowed detection of A. portunus in infected cells and qPCR assay provided accurate quantification of A. portunus in the samples. Transmission electron microscopy (TEM) images revealed that A. portunus could complete its entire life cycle and produce mature spores in RK13 cells. Additionally, we have identified novel life cycle characteristics during the development of A. portunus in RK 13 cells using TEM. These findings contribute to our understanding of new life cycle pathways of A. portunus. The establishment of an in vitro culture model for A. portunus is critical as it provides a valuable tool for understanding the molecular and immunological events that occur during infection. Furthermore, it will facilitate the development of effective treatment strategies for this intracellular pathogen.


Subject(s)
Brachyura , Microsporidia , Animals , Microsporidia/physiology , Microsporidia/genetics , Brachyura/parasitology , Brachyura/microbiology , Cell Line , In Situ Hybridization, Fluorescence
4.
Acta Psychol (Amst) ; 245: 104233, 2024 May.
Article in English | MEDLINE | ID: mdl-38522350

ABSTRACT

Online learning has become increasingly prevalent in the era of digitalization, impacted by both internet penetration and the COVID-19 pandemic. Classroom interaction, as a key factor in evaluating students' learning experience in online settings, has been identified to be associated with their academic achievement. While previous research has underscored the significance of classroom interaction in language learning settings, there is relatively limited research on its relationships with student satisfaction and learning. This research intends to explore classroom interaction and its mediating role in the correlation between student satisfaction and perceived online learning in online contexts. Given this, the paper reports a quantitative-method study that examined how Chinese EFL tertiary students perceived three types of classroom interaction (i.e., learner-learner, learner-instructor, and learner-content), their satisfaction, and its influences on their perceived online learning. Data was collected from 319 Chinese university students through convenience sampling and a self-designed questionnaire, and then analyzed with the help of SPSS. The results showed that: 1) the students had moderately positive perceptions of classroom interaction and online learning, but were neutral about their satisfaction; 2) positive correlations were observed between classroom interaction, student satisfaction, and online learning; and 3) student satisfaction predicted perceived online learning, with classroom interaction partially mediating this relationship. The findings of this research have implications for strengthening the effectiveness of online language teaching in the post-COVID-19 era.


Subject(s)
COVID-19 , Education, Distance , Humans , Pandemics , Students , Language
5.
Brain ; 147(5): 1644-1652, 2024 May 03.
Article in English | MEDLINE | ID: mdl-38428032

ABSTRACT

The pathological misfolding and aggregation of soluble α-synuclein into toxic oligomers and insoluble amyloid fibrils causes Parkinson's disease, a progressive age-related neurodegenerative disease for which there is no cure. HET-s is a soluble fungal protein that can form assembled amyloid fibrils in its prion state. We engineered HET-s(218-298) to form four different fibrillar vaccine candidates, each displaying a specific conformational epitope present on the surface of α-synuclein fibrils. Vaccination with these four vaccine candidates prolonged the survival of immunized TgM83+/- mice challenged with α-synuclein fibrils by 8% when injected into the brain to model brain-first Parkinson's disease or by 21% and 22% when injected into the peritoneum or gut wall, respectively, to model body-first Parkinson's disease. Antibodies from fully immunized mice recognized α-synuclein fibrils and brain homogenates from patients with Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. Conformation-specific vaccines that mimic epitopes present only on the surface of pathological fibrils but not on soluble monomers, hold great promise for protection against Parkinson's disease, related synucleinopathies and other amyloidogenic protein misfolding disorders.


Subject(s)
Mice, Transgenic , Parkinson Disease , alpha-Synuclein , Animals , Parkinson Disease/immunology , Parkinson Disease/pathology , Mice , alpha-Synuclein/immunology , alpha-Synuclein/metabolism , Humans , Amyloid/immunology , Amyloid/metabolism , Vaccination , Fungal Proteins/immunology , Brain/pathology , Brain/metabolism , Brain/immunology , Female , Mice, Inbred C57BL
6.
Parasit Vectors ; 17(1): 59, 2024 Feb 10.
Article in English | MEDLINE | ID: mdl-38341599

ABSTRACT

BACKGROUND: Toxoplasma gondii is an important protozoan pathogen with medical and veterinary importance worldwide. Drugs currently used for treatment of toxoplasmosis are less effective and sometimes cause serious side effects. There is an urgent need for the development of more effective drugs with relatively low toxicity. METHODS: The effect of tylosin on the viability of host cells was measured using CCK8 assays. To assess the inhibition of tylosin on T. gondii proliferation, a real-time PCR targeting the B1 gene was developed for T. gondii detection and quantification. Total RNA was extracted from parasites treated with tylosin and then subjected to transcriptome analysis by RNA sequencing (RNA-seq). Finally, murine infection models of toxoplasmosis were used to evaluate the protective efficacy of tylosin against T. gondii virulent RH strain or avirulent ME49 strain. RESULTS: We found that tylosin displayed low host toxicity, and its 50% inhibitory concentration was 175.3 µM. Tylsoin also inhibited intracellular T. gondii tachyzoite proliferation, with a 50% effective concentration of 9.759 µM. Transcriptome analysis showed that tylosin remarkably perturbed the gene expression of T. gondii, and genes involved in "ribosome biogenesis (GO:0042254)" and "ribosome (GO:0005840)" were significantly dys-regulated. In a murine model, tylosin treatment alone (100 mg/kg, i.p.) or in combination with sulfadiazine sodium (200 mg/kg, i.g.) significantly prolonged the survival time and raised the survival rate of animals infected with T. gondii virulent RH or avirulent ME49 strain. Meanwhile, treatment with tylosin significantly decreased the parasite burdens in multiple organs and decreased the spleen index of mice with acute toxoplasmosis. CONCLUSIONS: Our findings suggest that tylosin exhibited potency against T. gondii both in vitro and in vivo, which offers promise for treatment of human toxoplasmosis.


Subject(s)
Toxoplasma , Toxoplasmosis , Humans , Animals , Mice , Tylosin/pharmacology , Tylosin/therapeutic use , Toxoplasmosis/drug therapy , Toxoplasmosis/parasitology , Sulfadiazine/pharmacology , Sulfadiazine/therapeutic use , Spleen
7.
Food Res Int ; 179: 114021, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38342541

ABSTRACT

Sheep milk is rich in fat, protein, vitamins and minerals and is also one of the most important sources of natural bioactives. Several biopeptides in sheep milk have been reported to possess antibacterial, antiviral and anti-inflammatory properties, and they may prevent type 2 diabetes (T2D), disease and cancer. However, the precise mechanism(s) underlying the protective role of sheep milk against T2D development remains unclear. Therefore, in the current study, we investigated the effect of sheep milk on insulin resistance and glucose intolerance in high-fat diet (HFD)-fed mice, by conducting intraperitoneal glucose tolerance tests, metabolic cage studies, genomic sequencing, polymerase chain reaction, and biochemical assays. Hyperinsulinemic-euglycemic clamp-based experiments revealed that mice consuming sheep milk exhibited lower hepatic glucose production than mice in the control group. These findings further elucidate the mechanism by which dietary supplementation with sheep milk alleviates HFD-induced systemic glucose intolerance.


Subject(s)
Diabetes Mellitus, Type 2 , Glucose Intolerance , Insulin Resistance , Sheep , Mice , Animals , Diet, High-Fat/adverse effects , Glucose Intolerance/metabolism , Glucose Intolerance/prevention & control , Diabetes Mellitus, Type 2/prevention & control , Milk/metabolism
11.
Spectrochim Acta A Mol Biomol Spectrosc ; 309: 123817, 2024 Mar 15.
Article in English | MEDLINE | ID: mdl-38211445

ABSTRACT

Advances in precision medical diagnostics require accurate and sensitive characterization of pathogens. In particular, health conditions associated with protein misfolding require an identification of proteinaceous amyloid fibrils or their precursors. These pathogenic entities express specific molecular structures, which require ultra-sensitive, molecular-level detection methods. A potentially transformative technique termed nanoplasmonics employs electro-optical phenomena in the vicinity of specially engineered metal nanostructures. A signature application of nanoplasmonics exploits enhancement of inelastic scattering of light in specific locations near metallic nanostructures, known as surface-enhanced Raman scattering (SERS). We applied SERS complemented with confocal microscopy imaging for ultra-sensitive, non-invasive, and label-free characterization of the fungal prion HET-s (218-289) as a model for ß-sheet rich amyloid structures. This characterization employed Au-coated dielectric supports as plasmonic substrates. After confirming the formation of HET-s fibrils at both pH 7.5 and 2.8 using negative staining transmission electron microscopy, we subjected the fibril-containing solutions to multimodal analysis using confocal microscopy and SERS. The SERS spectral fingerprints from all HET-s samples expressed vibrational markers for ß-structure, unstructured backbone, and aromatic side-chains. However, relative intensities of major SERS bands were pronouncedly different for the two pH levels. We have analyzed potential origins of the most pronounced SERS bands and proposed hypothetical mechanistic models that could explain the observed SERS fingerprints from HET-s fibrils grown at pH 7.5 and 2.8.


Subject(s)
Prions , Prions/chemistry , Amyloid/chemistry , Hydrogen-Ion Concentration , Fungal Proteins/chemistry
12.
World J Psychiatry ; 13(11): 949-957, 2023 Nov 19.
Article in English | MEDLINE | ID: mdl-38073900

ABSTRACT

BACKGROUND: Traditional treatments for major depressive disorder (MDD), including medication and therapy, often fail and have undesirable side effects. Electroconvulsive therapy (ECT) uses electrical currents to induce brief seizures in the brain, resulting in rapid and potent antidepressant effects. However, owing to misconceptions and controversies, ECT is not as widely used as it could and often faces stigmatization. AIM: To evaluate the efficacy and safety of ECT compared to those of medication and/or therapy in patients with severe MDD. METHODS: This prospective cohort study included 220 individuals with severe MDD who were divided into the ECT and non-ECT groups. The patients in the ECT group underwent bilateral ECT three times a wk until they either achieved remission or reached a maximum of 12 sessions. The non-ECT group received medication and/or therapy according to clinical guidelines for MDD. The primary outcome was the variation in the hamilton depression rating scale (HDRS) score from treatment/ECT initiation to week 12. In addition, patients' quality of life, cognitive abilities, and biomarkers were measured throughout the study. RESULTS: Although both groups showed significant improvements in their HDRS scores over time, the improvement was more pronounced in the ECT group than in the non-ECT group. Additionally, the ECT group exhibited a more substantial improvement in the quality of life and cognitive function than those of the non-ECT group. Compared with the non-ECT group, the ECT group exhibited evi-dently lower variations in the brain-derived neurotrophic factor (BDNF) and cytokine interleukin-6 (IL-6) levels. The side effects were generally mild and comparable between the two groups. ECT is safer and more potent than medication and/or therapy in mitigating depressive symptoms, enhancing well-being, and bolstering cognitive capabilities in individuals with severe MDD. ECT may also affect the levels of BDNF and IL-6, which are indicators of neuroplasticity and inflammation, respectively. CONCLUSION: ECT has emerged as a potentially advantageous therapeutic approach for patients with MDD who are unresponsive to alternative treatments.

13.
Polymers (Basel) ; 15(22)2023 Nov 17.
Article in English | MEDLINE | ID: mdl-38006164

ABSTRACT

The thermal decomposition product of magnesium hydroxide (MH) is magnesium oxide (MgO), which serves as the foundational material for fireproof layer construction in the condensed phase. However, the weak interaction force between particles of MgO generated by thermal decomposition leads to the insufficient strength and poor adhesion ability of the fireproof layer. The fireproof layer was easily damaged and detached in this study, resulting in the low flame-retardant efficiency of MH. In this work, polycarbosilane (PCS) and divinyl benzene (DVB) were used to modify MH, and EVA/MH/PCS/DVB composites were made via melt blending. The flame-retardant properties of EVA/MH/PCS/DVB were evaluated using the limiting oxygen index (LOI), vertical combustion (UL-94), and a cone calorimeter (CONE). The thermal stability of the composites and flame retardants was analyzed using a thermogravimetric analyzer. The char layer structure was observed and analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that the LOI of the EVA/MH/PCS/DVB with 50 wt.% flame retardants in total was as high as 65.1, which increased by 160% in comparison with EVA/MH. Furthermore, the total smoke production (TSP) of the EVA/MH/PCS/DVB composite decreased by 22.7% compared to EVA/MH/PCS; the thermal stability of the MH/PCS/DVB and EVA/MH/PCS/DVB improved to some extent; and the compact residual char after the combustion of EVA/MH/PCS/DVB had fewer cracks due to the adhesive effect induced by PCS/DVB.

14.
J Agric Food Chem ; 71(43): 16102-16113, 2023 Nov 01.
Article in English | MEDLINE | ID: mdl-37856320

ABSTRACT

Four human milk oligosaccharides (HMOs), 3'-sialyllactose (3'-SL), 6'-sialyllactose (6'-SL), 2'-fucosyllactose (2'-FL), and 3-fucosyllactose (3-FL), were assessed for their possible antiviral activity against the SARS-CoV-2 spike receptor binding domain (RBD) in vitro. Among them, only 2'-FL/3-FL exhibited obvious antibinding activity against direct binding and trans-binding in competitive immunocytochemistry and enzyme-linked immunosorbent assays. The antiviral effects of 2'-FL/3-FL were further confirmed by pseudoviral assays with three SARS-Cov-2 mutants, with a stronger inhibition effect of 2'-FL than 3-FL. Then, 2'-FL/3-FL were studied with molecular docking and microscale thermophoresis analysis, showing that the binding sites of 2'-FL on RBD were involved in receptor binding, in addition to a tighter bond between them, thus enabling 2'-FL to be more effective than 3-FL. Moreover, the immunomodulation effect of 2'-FL was preliminary evaluated and confirmed in a human alveolus chip. These results would open up possible applications of 2'-FL for the prevention of SARS-CoV-2 infections by competitive binding inhibition.


Subject(s)
COVID-19 , Milk, Human , Humans , Milk, Human/chemistry , SARS-CoV-2 , Molecular Docking Simulation , Oligosaccharides/pharmacology , Oligosaccharides/analysis , Antiviral Agents/pharmacology
15.
BMC Psychol ; 11(1): 318, 2023 Oct 07.
Article in English | MEDLINE | ID: mdl-37805631

ABSTRACT

BACKGROUND: Teacher-student interactions and proximity have been shown influential in second/foreign (L2) education. However, the role of L2 teachers' immediacy behaviors on students' willingness to communicate (WTC) and academic engagement remains relatively unexamined in the context of English as a foreign language (EFL). PURPOSE: This study intended to examine the association among EFL teachers' immediacy behaviors and students' WTC and engagement. METHODS: In this quantitative study, three online questionnaires were completed by 400 Chinese EFL students in different universities out of which 364 were valid. RESULTS: The results of statistical analysis and structural equation modeling (SEM) indicated that teachers' immediacy behaviors (verbal, nonverbal) had a highly significant influence on EFL students' WTC (ß=0.89, p = .000) and academic engagement (ß=0.71, p = .000). It was also revealed that teachers' immediacy could predict 89% and 71% of variances in students' WTC academic engagement, respectively. CONCLUSIONS: Based on the results, I could be concluded that EFL teachers' interpersonal communication abilities (e.g., immediacy) foster the establishment and growth of other positive outcomes among learners. IMPLICATIONS: The study presents some conclusions and practical implications for EFL teachers, materials developers, and trainers to integrate the nonverbal cues of L2 communication into their practices. Such practices have the potential to enhance students' willingness to communicate (WTC) and improve academic engagement.


Subject(s)
Educational Personnel , Language , Humans , Students , Communication , Asian People
16.
Rev Sci Instrum ; 94(10)2023 Oct 01.
Article in English | MEDLINE | ID: mdl-37787632

ABSTRACT

In this paper, the effects of initial electrons generation approaches on nanosecond pulsed breakdown characteristics are analyzed. Based on the numerical simulations with a 3D PIC-MCC model, the impacts of field-enhancement factor and initial electron concentration on nanosecond pulsed breakdown characteristics are investigated. Three types of switches are designed and subjected to testing under pulse voltages with rise times of 40, 70, and 120 ns, respectively. The results can be summarized as follows. First, the field-enhancement factor and initial electron concentration have significant influences on the development of the discharge channel. Second, the cathode-grooved self-triggered switch exhibits lower breakdown time delay jitter than the hemispherical self-breakdown switch at low pressure, while the differences in jitter between the two switches become negligible at high pressure. Third, the cathode-grooved self-triggered switch shows a lower breakdown time delay jitter compared to the pre-ionization self-triggered switch for pulse voltages with rise times of 40 and 70 ns. Conversely, this trend reverses for pulse voltage with a rise time of 120 ns. Finally, the breakdown time delay jitter for both the cathode-grooved self-triggered switch and the pre-ionization self-triggered switch has been reduced, and both switches are suitable for different operating requirements and conditions.

17.
Int J Mol Sci ; 24(17)2023 Sep 03.
Article in English | MEDLINE | ID: mdl-37686427

ABSTRACT

Lysin-Motif receptor-like kinase (LysM-RLK) proteins are widely distributed in plants and serve a critical role in defending against pathogens and establishing symbiotic relationships. However, there is a lack of comprehensive identification and analysis of LysM-RLK family members in the soybean genome. In this study, we discovered and named 27 LysM-RLK genes in soybean. The majority of LysM-RLKs were highly conserved in Arabidopsis and soybean, while certain members of subclades III, VI, and VII are unique to soybean. The promoters of these LysM-RLKs contain specific cis-elements associated with plant development and responses to environmental factors. Notably, all LysM-RLK gene promoters feature nodule specificity elements, while 51.86% of them also possess NBS sites (NIN/NLP binding site). The expression profiles revealed that genes from subclade V in soybean roots were regulated by both rhizobia and nitrogen treatment. The expression levels of subclade V genes were then validated by real-time quantitative PCR, and it was observed that the level of GmLYK4a and GmLYK4c in roots was inhibited by rhizobia but induced via varying concentrations of nitrate. Consequently, our findings provide a comprehensive understanding of the soybean LysM-RLK gene family and emphasize the role of subclade V in coupling soybean symbiotic nitrogen fixation and nitrogen response.


Subject(s)
Arabidopsis , Glycine max , Glycine max/genetics , Protein-Tyrosine Kinases , Arabidopsis/genetics , Binding Sites , Nitrogen
18.
Chemosphere ; 340: 139846, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37598945

ABSTRACT

The selenium (Se)-deficient soil belt in China has gained widespread attention. During large-scale soil surveys in China, Se-rich soils within low-Se belts have been identified. However, the sources of Se in those soils and the controlling factors for their enrichment remain unclear. Here we summarize Se concentrations and spatial distributions in the Yuanzhou district of the Loess Plateau. We evaluated Se variations in soil profiles, Se migration into water bodies, and considered soil indicators, topographic characteristics and the influence of land-use types on soil Se concentrations. The average Se concentration in the topsoil of the Yuanzhou district was 0.164 µg/g. High-Se soils (>0.222 µg/g) were found in the western valley plain and the southern red bed hilly area, as well as sporadically in higher elevation forestland and grassland areas in the east. Enrichment of Se in the topsoil in the eastern and southern areas was primarily due to Se adsorption and accumulation by soil organic matter as well as enrichment in gypsum, berlinite, and clay minerals during soil formation. Widespread enrichment in the southern area was linked to high Se concentrations in red Tertiary sedimentary rocks. In the western area, enrichment of Se in topsoil was found on both sides of the Qingshui River at low elevations with gentle slopes, with river water being the primary carrier of Se enrichment. These findings provide valuable insights into the epigenetic geochemical behavior of soil Se in China's low-Se belt that accounts for development of Se-rich soils in the region.


Subject(s)
Selenium , Soil , China , Forests , Water
19.
J Clin Pediatr Dent ; 47(4): 86-94, 2023 Jul.
Article in English | MEDLINE | ID: mdl-37408351

ABSTRACT

Iron deficiency anemia (IDA) is a common nutritional disease associated with early childhood caries. This study aimed to explore the role of iron levels in pathological changes of dental caries in childhood. Rats were divided into four groups based on their iron content: IDA, positive control (PC), high iron (HI), and negative control (NC). Except for the rats in the NC group, rats in the other groups were inoculated with Streptococcus mutans and fed cariogenic high-sugar fodder to induce caries. Three months later, the caries status of the molars was evaluated at both the smooth and sulcal surfaces according to Keyes scores. Scanning electron microscopy (SEM) was performed to reveal microstructural changes in caries. Energy-dispersive spectroscopy (EDS) was used to determine the elemental composition of the enamel and dentin. In addition, the histopathology of the salivary gland was detected using hematoxylin and eosin (HE) staining.The results showed that rats in the PC group exhibited obvious carious lesions. The carious score was significantly higher in the IDA group than in the PC group but was lower in the HI group. SEM revealed complete destruction of the enamel and damage to the middle dentin in the IDA group. In contrast, the molars in the HI group exhibited some degree of enamel demineralization, but the underlying dentin was almost intact. In addition, the elemental compositions of the enamel and dentin were similar among the four groups, and iron was detected only in the HI group. No differences were observed in the morphological structures of the salivary glands of rats from the different groups. In conclusion, ID enhanced the pathological damage of caries, whereas HI weakened it. Iron may participate in the pathological damage caused by childhood caries by affecting enamel mineralization.


Subject(s)
Dental Caries , Child, Preschool , Rats , Humans , Animals , Dental Caries/pathology , Dental Enamel/pathology , Streptococcus mutans , Molar/pathology , Iron/analysis , Dentin/pathology
20.
Materials (Basel) ; 16(13)2023 Jun 30.
Article in English | MEDLINE | ID: mdl-37445072

ABSTRACT

Silica nanoparticles (nano-silica) were used as synergistic agents with ammonium polyphosphate (APP) and pentaerythritol (PER) to enhance flame retardancy of polypropylene (PP) in this research. The composites were prepared using a melt-mixing method. The influences of nano-silica on the fire performance of composites were thoroughly discussed, which promotes understanding of nano-silica on the flame-retardant performance of polypropylene composite. Scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS) results indicated that the nano-silica with a diameter of about 95 ± 3.9 nm were dispersed favorably in the composite matrix, which might elevate its synergistic effect with intumescent flame retardant and improve the flame retardancy of polypropylene composite. The synergistic effects between nano-silica and intumescent flame retardant on PP composites were studied using the limiting oxygen index (LOI), UL-94 test, and cone calorimeter test (CCT). The total amount of flame retardant was maintained at 30%. When the dosage of nano-silica was 1 wt.%, the LOI value of PP/IFR/Si1.0 composite reached 27.3% and its UL-94 classification reached V-1. Based on the parameters of the CCT, the introduction of nano-silica induced composites with depressed heat release rate (HRR) and peak heat release rate (PHRR). The PHRR of PP/IFR/Si0.5 was only 295.8 kW/m2, which was 17% lower than that of PP/IFR. Moreover, the time to PHRR of PP/IFR/Si0.5 was delayed to 396 s, which was about 36 s later than that without nano-silica. EDS was used to quantitatively analyze the distribution of silica in charred residue. The EDS results indicated that the silica tended to accumulate on the surface during the fire. The surface accumulation characteristic of silica endows it with the enhanced flame-retardant properties of polypropylene composite at a very small dosage (as low as 1 wt.%).

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