Broadband Visible Light-Absorbing [70]Fullerene-BODIPY-Triphenylamine Triad: Synthesis and Application as Heavy Atom-Free Organic Triplet Photosensitizer for Photooxidation.

A broadband visible light-absorbing [70]fullerene-BODIPY-triphenylamine triad (C70-B-T) has been synthesized and applied as a heavy atom-free organic triplet photosensitizer for photooxidation. By attaching two triphenylmethyl amine units (TPAs) to the π-core of BODIPY via ethynyl linkers, the absorption range of the antenna is extended to 700 nm with a peak at 600 nm. Thus, the absorption spectrum of C70-B-T almost covers the entire UV-visible region (270-700 nm). The photophysical processes are investigated by means of steady-state and transient spectroscopies. Upon photoexcitation at 339 nm, an efficient energy transfer (ET) from TPA to BODIPY occurs both in C70-B-T and B-T, resulting in the appearance of the BODIPY emission at 664 nm. Direct or indirect (via ET) excitation of the BODIPY-part of C70-B-T is followed by photoinduced ET from the antenna to C70, thus the singlet excited state of C70 (1C70*) is populated. Subsequently, the triplet excited state of C70 (3C70*) is produced via the intrinsic intersystem crossing of C70. The photooxidation ability of C70-B-T was studied using 1,5-dihydroxy naphthalene (DHN) as a chemical sensor. The photooxidation efficiency of C70-B-T is higher than that of the individual components of C70-1 and B-T, and even higher than that of methylene blue (MB). The photooxidation rate constant of C70-B-T is 1.47 and 1.51 times as that of C70-1 and MB, respectively. The results indicate that the C70-antenna systems can be used as another structure motif for a heavy atom-free organic triplet photosensitizer.

Phenotypic and genotypic spectrum of noonan syndrome: A retrospective analysis of 46 consecutive pediatric patients presented at a regional cardiac center in China.

Background: Noonan syndrome (NS) is relatively common but poorly recognized. We aimed to describe the phenotypic and genotypic spectrum of NS in a Chinese cohort. Method: The study retrospectively investigated consecutive pediatric patients who presented at the Guangdong cardiovascular institute between 2018 and 2020 with confirmed known NS-relevant mutations determined by exome sequencing. Dates of genetic testing, Age, sex, institution of genetic testing, mutated gene (related to NS) and its classification, heterozygosity, and parental origin were identified from the sequencing reports. Facial features, cardiac defect and other clinical characteristics were also assessed. Comparisons of categorical variables between groups were examined by Chi-square test or Fisher's exact test when appropriate. Intraclass correlation coefficient (ICC) was performed to evaluate the reliability of evaluation of facial features between different evaluators. Results: The most prevalent mutated genes were PTPN11 (37.0%) and RAF1 (19.6%), and most mutations were pathogenic (67.4%) and de novo (87.0%). Most patients were with NS-relevant facial features (97.4%) and cardiac defects (92.7%), where ventricular hypertrophy, pulmonary valve stenosis, and atrial septal defect were the most prevalent. Patients with mutated RAF1 appeared to be diagnosed at an older age than those with mutated PTPN11, and with higher prevalence of mitral regurgitation, hypertrophic cardiomyopathy, and ventricular hypertrophy, but lower prevalence of pulmonary valve stenosis and pulmonary artery stenosis. Patients presented at an age ≥2 years appeared to be with fewer NS-relevant facial features and cardiac defects than those aged <2 years. Conclusions: These findings indicated featured distributions of phenotypic and genotypic spectrum in Chinese pediatric patients, which might be helpful for early NS diagnosis.

Extranodal metastasis is a powerful prognostic factor in patients with adenocarcinoma of the esophagogastric junction.

BACKGROUND AND OBJECTIVES: The purpose of this study is to estimate the effect of extranodal metastasis (EM) on recurrence and survival in patients with adenocarcinoma of the esophagogastric junction (AEG) after curative resection. METHODS: Clinical data from 284 node-positive AEG patients who underwent curative resection were reviewed. Univariate and multivariate analyses were conducted to elucidate the effect of EM on recurrence-free survival (RFS) and overall survival (OS). RESULTS: EM was detected in 70 (24.6%) of the 284 cases. It had a significant correlation with tumor size, Lauren type, histopathological grading, depth of tumor invasion, number of metastatic nodes, lymph node ratio, and TNM stage. The 5-year RFS and OS rates were 22.2% and 24.3%, respectively. Patients with EM had a significantly decreased RFS (16 vs. 36 months, P < 0.001) and OS (23 vs. 41 months, P < 0.001) compared with those without EM. Multivariate analyses identified EM as an independent prognostic factor (P = 0.003 and 0.001, respectively). CONCLUSION: The presence of EM increases recurrence probability and reduces OS probability of AEG patients with lymph node metastasis. EM is a powerful prognostic factor reflecting a particularly aggressive biological behavior. Better understanding of EM status can help clinicians with regard to treatment decision and prognosis evaluation.

[Risk factors of early recurrence and prognosis for patients with adenocarcinoma of gastroesophageal junction after curative resection].

OBJECTIVE: To investigate the risk factors for early recurrence of gastroesophageal junction adenocarcinoma (Siewert type II/III) after curative resection and the prognosis of these patients. METHODS: Retrospective analysis was performed for the 170 patients with recurrent AEG after curative resection in our hospital.Univariate and multivariate analysis were applied to investigate risk factors for early recurrence ( < 24 month), the prognosis of these patients were also analyzed. RESULTS: The rate of early recurrence of AEG after curative resection was 75.3%. Univariate analysis showed that tumor Borrmann type, invasive depth, lymph node metastasis, metastasis lymph node ratio (LNR) and TNM stage were significant factors associated with early recurrence after curative resection (P < 0.05). Multivariate analysis identified that only LNR and tumor invasive depth were independent risk factors for early recurrence (P < 0.05). The median disease free survival time (9, 20 months, P < 0.01), 5-year survival rate (2.4%, 12.6%, P < 0.01) and the median survival time after recurrence(5, 8 months, P = 0.004) between patients with high-LNR group and low-LNR group were significantly difference. CONCLUSIONS: LNR and tumor invasive depth were determined to be independent risk factors associate with early recurrence after curative resection for AEG. The patients with high-LNR have a poorer survival compared with those with low-LNR; For the patients with serosa invaded and high LNR should be closely followed up to detect recurrence and take effective treatment timely to improve patients outcomes.

[Analysis of the clinicopathologic characters and prognostic impact of extranodal metastasis in gastric cardia patients].

OBJECTIVE: To investigate the correlation between extranodal metastasis (EM) and clinicopathologic features as well as the effect of EM on the prognosis in gastric cardia patients. METHODS: Retrospective analysis was performed for the 323 cases with histologically proven adenocarcinoma of gastric cardia who underwent curative resection from January 2000 to January 2007. There were 272 male patients and 51 female patients with their median age of 63 (22 to 85) years. The relationship between clinicopathological features and extranodal metastasis was studied. The effects of the EM on the recurrence and survival of these patients were also analyzed. RESULTS: EM positive was detected in 67 (20.7%) of the 323 patients. The incidence of EM was correlated with tumor Lauren typing, differentiation degree, invasive depth and lymph node metastasis (χ(2) = 4.647-27.216, P < 0.05). The 5-year survival rate and media survival time between patients with EM and those without EM were 12.3%, 34.1% and 20, 39 months, there was a statistically significantly difference (χ(2) = 23.936, P = 0.000) in 5-year survival rate. Multivariate analysis identified that invasive depth, lymph node metustasis and EM as an independent prognostic factor of all the patients. To the last follow up, the cumulative probability of recurrence of EM-positive patients was significant higher than EM-negative patients (59.7% vs. 35.9%; χ(2) = 12.409, P = 0.000). To study furthermore, stratified analysis showed that, in the node-positive patients, the cumulative recurrence rate of EM-positive patients was higher than EM-negative patients (60.9% vs. 40.0%; χ(2) = 8.410, P = 0.004) and the 5-year survival rate of EM-positive patients was less than the EM-negative patients (12.9% vs. 30.1%; χ(2) = 12.939, P = 0.000), the differences were statistically significant. CONCLUSIONS: EM positive is determined to be an independent prognosis factor of gastric cardia after curative resection. EM-positive patients have a high risk for recurrence and a short time to live.

Effectiveness and safety of traditional Chinese medicine for diabetic retinopathy: A systematic review and network meta-analysis of randomized clinical trials.

BACKGROUND: Diabetic retinopathy (DR) is currently recognized as one of the most serious diabetic microangiopathies and a major cause of adult blindness. Commonly used clinical approaches include etiological control, microvascular improvement, and surgical intervention, but they are ineffective and have many side effects. Oral Chinese medicine (OCM) has been used for thousands of years to treat DR and is still widely used today, but it is unclear which OCM is more effective for DR. AIM: To estimate relative effectiveness and safety profiles for different classes of OCMs for DR, and provide rankings of the available OCMs. METHODS: The search time frame was from the creation of the database to January 2023. RevMan 5.3 and Stata 14.0 software were used to perform the systematic review and Network meta-analyses (NMA). RESULTS: A total of 107 studies and 9710 patients were included, including 4767 cases in the test group and 4973 cases in the control group. Based on previous studies and clinical reports, and combined with the recommendations of Chinese guidelines for the prevention and treatment of DR, 9 OCMs were finally included in this study, namely Compound Xueshuantong Capsules, Qiming Granules, Compound Danshen Dripping Pills, Hexue Mingmu Tablets (HXMM), Qiju Dihuang Pills (QJDH), Shuangdan Mingmu Capsules (SDMM), Danggui Buxue Decoction (DGBX), Xuefu Zhuyu Decoction and Buyang Huanwu Decoction. When these nine OCMs were analyzed in combination with conventional western medicine treatment (CT) compared with CT alone, the NMA results showed that HXMM + CT has better intervention effect on the overall efficacy of DR patients, HXMM + CT has better effect on improving patients' visual acuity, SDMM + CT has better effect on inhibiting vascular endothelial growth factor, DGBX + CT has better effect on reducing fundus hemorrhage area, HXMM + CT has better effect on reducing fasting blood glucose, and QJDH + CT has better effect on reducing glycated hemoglobin. When there are not enough clinical indicators for reference, SDMM + CT or HXMM + CT treatments can be chosen because they are effective for more indicators and demonstrate multidimensional efficacy. CONCLUSION: This study provides evidence that combining OCMs with CT leads to better outcomes in all aspects of DR compared to using CT alone. Based on the findings, we highly recommend the use of SDMM or HXMM for the treatment of DR. These two OCMs have demonstrated outstanding efficacy across multiple indicators.

Emotional Contagion: Research on the Influencing Factors of Social Media Users' Negative Emotional Communication During the COVID-19 Pandemic.

During the epidemic, social media platforms were frequently used by users to express and spread negative emotions. Under emotional contagion, individual emotions gradually generalized into group emotions. At the same time, the public could not regulate their emotions and lacked access to release them rationally. This study explores the factors influencing the negative emotions' communication among social media users during the COVID-19 epidemic from the perspective of emotion contagion theory to discover the psychological mechanisms among the public. The questionnaire was tested for reliability and validity and then distributed online on Chinese social media platforms, and the data collected were statistically analyzed. The findings show that there are significant differences in negative emotional communication in social media among different age groups; the seven dimensions of deindividuation, risk perception, group identity, group efficacy, event stimulation, event publicness, and emotion contagion all have significant positive effects on users' negative emotional communication. This study aims to raise public awareness of negative emotions and promote the reconstruction and recovery of public mental health in the epidemic era.

Recent Advances in Zinc Hydroxystannate-Based Flame Retardant Polymer Blends.

During the combustion of polymeric materials, plenty of heat, smoke, and toxic gases are produced that may cause serious harm to human health. Although the flame retardants such as halogen- and phosphorus-containing compounds can inhibit combustion, they cannot effectively reduce the release of toxic fumes. Zinc hydroxystannate (ZHS, ZnSn(OH)6) is an environmentally friendly flame retardant that has attracted extensive interest because of its high efficiency, safety, and smoke suppression properties. However, using ZHS itself may not contribute to the optimal flame retardant effect, which is commonly combined with other flame retardants to achieve more significant efficiency. Few articles systematically review the recent development of ZHS in the fire safety field. This review aims to deliver an insight towards further direction and advancement of ZHS in flame retardant and smoke suppression for multiple polymer blends. In addition, the fire retarded and smoke suppression mechanism of ZHS will be demonstrated and discussed in depth.

Automated Facial Recognition for Noonan Syndrome Using Novel Deep Convolutional Neural Network With Additive Angular Margin Loss.

BACKGROUND: Noonan syndrome (NS), a genetically heterogeneous disorder, presents with hypertelorism, ptosis, dysplastic pulmonary valve stenosis, hypertrophic cardiomyopathy, and small stature. Early detection and assessment of NS are crucial to formulating an individualized treatment protocol. However, the diagnostic rate of pediatricians and pediatric cardiologists is limited. To overcome this challenge, we propose an automated facial recognition model to identify NS using a novel deep convolutional neural network (DCNN) with a loss function called additive angular margin loss (ArcFace). METHODS: The proposed automated facial recognition models were trained on dataset that included 127 NS patients, 163 healthy children, and 130 children with several other dysmorphic syndromes. The photo dataset contained only one frontal face image from each participant. A novel DCNN framework with ArcFace loss function (DCNN-Arcface model) was constructed. Two traditional machine learning models and a DCNN model with cross-entropy loss function (DCNN-CE model) were also constructed. Transfer learning and data augmentation were applied in the training process. The identification performance of facial recognition models was assessed by five-fold cross-validation. Comparison of the DCNN-Arcface model to two traditional machine learning models, the DCNN-CE model, and six physicians were performed. RESULTS: At distinguishing NS patients from healthy children, the DCNN-Arcface model achieved an accuracy of 0.9201 ± 0.0138 and an area under the receiver operator characteristic curve (AUC) of 0.9797 ± 0.0055. At distinguishing NS patients from children with several other genetic syndromes, it achieved an accuracy of 0.8171 ± 0.0074 and an AUC of 0.9274 ± 0.0062. In both cases, the DCNN-Arcface model outperformed the two traditional machine learning models, the DCNN-CE model, and six physicians. CONCLUSION: This study shows that the proposed DCNN-Arcface model is a promising way to screen NS patients and can improve the NS diagnosis rate.

Automatic Facial Recognition of Williams-Beuren Syndrome Based on Deep Convolutional Neural Networks.

Background: Williams-Beuren syndrome (WBS) is a rare genetic syndrome with a characteristic "elfin" facial gestalt. The "elfin" facial characteristics include a broad forehead, periorbital puffiness, flat nasal bridge, short upturned nose, wide mouth, thick lips, and pointed chin. Recently, deep convolutional neural networks (CNNs) have been successfully applied to facial recognition for diagnosing genetic syndromes. However, there is little research on WBS facial recognition using deep CNNs. Objective: The purpose of this study was to construct an automatic facial recognition model for WBS diagnosis based on deep CNNs. Methods: The study enrolled 104 WBS children, 91 cases with other genetic syndromes, and 145 healthy children. The photo dataset used only one frontal facial photo from each participant. Five face recognition frameworks for WBS were constructed by adopting the VGG-16, VGG-19, ResNet-18, ResNet-34, and MobileNet-V2 architectures, respectively. ImageNet transfer learning was used to avoid over-fitting. The classification performance of the facial recognition models was assessed by five-fold cross validation, and comparison with human experts was performed. Results: The five face recognition frameworks for WBS were constructed. The VGG-19 model achieved the best performance. The accuracy, precision, recall, F1 score, and area under curve (AUC) of the VGG-19 model were 92.7 ± 1.3%, 94.0 ± 5.6%, 81.7 ± 3.6%, 87.2 ± 2.0%, and 89.6 ± 1.3%, respectively. The highest accuracy, precision, recall, F1 score, and AUC of human experts were 82.1, 65.9, 85.6, 74.5, and 83.0%, respectively. The AUCs of each human expert were inferior to the AUCs of the VGG-16 (88.6 ± 3.5%), VGG-19 (89.6 ± 1.3%), ResNet-18 (83.6 ± 8.2%), and ResNet-34 (86.3 ± 4.9%) models. Conclusions: This study highlighted the possibility of using deep CNNs for diagnosing WBS in clinical practice. The facial recognition framework based on VGG-19 could play a prominent role in WBS diagnosis. Transfer learning technology can help to construct facial recognition models of genetic syndromes with small-scale datasets.

Genetic syndromes screening by facial recognition technology: VGG-16 screening model construction and evaluation.

BACKGROUND: Many genetic syndromes (GSs) have distinct facial dysmorphism, and facial gestalts can be used as a diagnostic tool for recognizing a syndrome. Facial recognition technology has advanced in recent years, and the screening of GSs by facial recognition technology has become feasible. This study constructed an automatic facial recognition model for the identification of children with GSs. RESULTS: A total of 456 frontal facial photos were collected from 228 children with GSs and 228 healthy children in Guangdong Provincial People's Hospital from Jun 2016 to Jan 2021. Only one frontal facial image was selected for each participant. The VGG-16 network (named after its proposal lab, Visual Geometry Group from Oxford University) was pretrained by transfer learning methods, and a facial recognition model based on the VGG-16 architecture was constructed. The performance of the VGG-16 model was evaluated by five-fold cross-validation. Comparison of VGG-16 model to five physicians were also performed. The VGG-16 model achieved the highest accuracy of 0.8860 ± 0.0211, specificity of 0.9124 ± 0.0308, recall of 0.8597 ± 0.0190, F1-score of 0.8829 ± 0.0215 and an area under the receiver operating characteristic curve of 0.9443 ± 0.0276 (95% confidence interval: 0.9210-0.9620) for GS screening, which was significantly higher than that achieved by human experts. CONCLUSIONS: This study highlighted the feasibility of facial recognition technology for GSs identification. The VGG-16 recognition model can play a prominent role in GSs screening in clinical practice.

Reversal of Chemotherapy Resistance to Cisplatin in NSCLC by miRNA-195-5p via Targeting the FGF2 Gene.

OBJECTIVE: To explore the mechanism of miR-195-5p in the pathogenesis non-small cell lung cancer (NSCLC) and cisplatin resistance. METHODS: The function of miR-195-5p in NSCLC and cisplatin resistance were determined by MTT, scratch assay, transwell assay, and nude mice xenograft experiments. miR-195-5p target gene was identified by dual-luciferase reporter assays and real-time PCR analysis. RESULTS: miR-195-5p content was lower in A549/DDP than that in A549 cells, with reduced chemotherapy sensitivity and increased cell invasion and migration ability. The loss-of-function and gain-of-function assays illustrated that miR-195-5p might have increased the chemosensitivity to cisplatin in the A549/DDP cells and decreased cell migration and invasion. FGF2 is a negatively correlated action target of miR-195-5p. miR-195-5p might affect EMT by inhibiting FGF2. Overexpression of FGF2 resulted in enhanced cisplatin resistance in the cells, while miR-195-5p might have reversed this resistance. CONCLUSION: Overall, miR-195-5p might target FGF2 to reduce cisplatin resistance in A549/DDP cells and enhance chemosensitivity.

Adjuvant radiotherapy for patients with pathologic node-negative esophageal carcinoma: A population based propensity matching analysis.

BACKGROUND: The impact of adjuvant treatment for esophageal carcinoma with tumor-negative lymph nodes after upfront radical esophagectomy is still uncertain. This study investigated the effects of postoperative radiotherapy in pT1-3N0 esophageal carcinoma after radical resection. METHOD: We retrospectively identified pT1-3N0M0 esophageal carcinoma patients between 2000 and 2016 from the Surveillance, Epidemiology, and End Results database. Patients with upfront esophagectomy were categorized as having received surgery alone (SA) and surgical resection followed by adjuvant radiotherapy (SA + RT). Propensity score matching, univariate and multivariate analysis were performed to compare overall survival (OS) and cause-specific survival (CSS). RESULTS: A total of 2862 patients were identified, of whom 274 received SA + RT and 2588 received SA. The median follow-up was 60.4 months (95%CI, 58.7-62.1 months). The five-year OS and CSS were better for SA group compared with SA + RT group (P < 0.001, respectively). Furthermore, after matching, the OS and CSS were still significantly better for SA patients. For T subgroup analysis, postoperative radiotherapy was an independent prognostic factor only for pT1 patients with worse OS, without survival differences for pT2 and pT3 patients. However, after multivariate cox analysis, postoperative radiotherapy can provide significantly better OS for pT3 patients with tumor length ≥5 cm (P = 0.03; 95%CI, 0.29-0.94). CONCLUSIONS: Among pT1-3N0M0 esophageal carcinoma patients, postoperative radiotherapy can provide significantly better OS for pT3 patients with tumor length ≥5 cm. However, there are no survival benefits for pT1-2 patients after SA + RT procedure. This finding may have significant implications on the use of adjuvant radiation in patients with pN0 disease.

MXene/chitosan nanocoating for flexible polyurethane foam towards remarkable fire hazards reductions.

MXene/chitosan nanocoating for flexible polyurethane foam (PUF) was prepared via layer-by-layer (LbL) approach. MXene (Ti3C2) ultra-thin nanosheets were obtained through etching process of Ti3AlC2 followed by exfoliation. The deposition of MXene/chitosan nanocoating was conducted by alternatingly immersing the PUF into a chitosan solution and a Ti3C2 aqueous dispersion, which resulted in different number of bilayers (BL) ranging from 2, 5 and 8. Owing to the utilization of ultra-thin Ti3C2 nanosheets, the weight gain was only 6.9% for 8 BL coating of PUF, which minimised the unfavourable impact on the intrinsic properties of PUF. The Ti3C2/chitosan coating significantly reduced the flammability and smoke releases of PUF. Compared with unmodified PUF, the 8 BL coating reduced the peak heat release rate by 57.2%, alongside with a 65.5% reduction in the total heat release. The 8 BL coating also showed outstanding smoke suppression ability with total smoke release decreased by 71.1% and peak smoke production rate reduced by 60.3%, respectively. The peak production of CO and CO2 gases also decreased by 70.8% and 68.6%, respectively. Furthermore, an outstanding char formation performance of 37.2 wt.% residue was obtained for 8 BL coated PUF, indicating the excellent barrier and carbonization property of the hybrid coating.

An analysis of research hotspots and modeling techniques on carbon capture and storage.

With the significant role that carbon capture and storage (CCS) could play in limiting the future temperature increase to below 2 °C higher than pre-industrialization levels, a growing research interest of CCS is attracted to the environmental, economic, and social field. However, a bibliometric analysis-based comprehensive review of CCS which covers mainly all industry sectors and all regions of the globe has not been made yet. To provide deeper insight into the research trends, this study employs a bibliometric analysis to examine the basic features of the literature from 1997 to 2017 and identifies the key research hotspots and modeling techniques by reviewing the current status and new efforts. Based on the analysis of the temporal and spatial trends, disciplines and journals distribution, institutions, authors, and citations, the publications relating to the environmental, economic and social aspects of CCS are assessed. The results indicate that the total number of publications has rapidly increased since 2006 and entered a stable stage. The most productive country, journal, institute, and author are the USA, International Journal of Greenhouse Gas Control, United State Department of Energy, and Rubin E S, respectively. Based on the co-occurrence analysis of keywords, five hot research topics in CCS are recognized, including tackling climate change, CCS technology prospects, cost estimates, sectoral applications, and social attitudes. In addition, three main methodologies including life cycle analysis, optimization methods, and real options methods used in quantifying the social, economic, and environmental impacts of CCS are thoroughly refined based on selection, limitation, and improvement. Finally, the recommendations for CCS future work concerning environmental, economic, and social aspects are proposed.

Functionalization of MXene Nanosheets for Polystyrene towards High Thermal Stability and Flame Retardant Properties.

Fabricating high-performance MXene-based polymer nanocomposites is a huge challenge because of the poor dispersion and interfacial interaction of MXene nanosheets in the polymer matrix. To address the issue, MXene nanosheets were successfully exfoliated and subsequently modified by long-chain cationic agents with different chain lengths, i.e., decyltrimethylammonium bromide (DTAB), octadecyltrimethylammonium bromide (OTAB), and dihexadecyldimethylammonium bromide (DDAB). With the long-chain groups on their surface, modified Ti3C2 (MXene) nanosheets were well dispersed in N,N-dimethylformamide (DMF), resulting in the formation of uniform dispersion and strong interfacial adhesion within a polystyrene (PS) matrix. The thermal stability properties of cationic modified Ti3C2/PS nanocomposites were improved considerably with the temperatures at 5% weight loss increasing by 20 °C for DTAB-Ti3C2/PS, 25 °C for OTAB-Ti3C2/PS and 23 °C for DDAB-Ti3C2/PS, respectively. The modified MXene nanosheets also enhanced the flame-retardant properties of PS. Compared to neat PS, the peak heat release rate (PHRR) was reduced by approximately 26.4%, 21.5% and 20.8% for PS/OTAB-Ti3C2, PS/DDAB-Ti3C2 and PS/DTAB-Ti3C2, respectively. Significant reductions in CO and CO2 productions were also obtained in the cone calorimeter test and generally lower pyrolysis volatile products were recorded by PS/OTAB-Ti3C2 compared to pristine PS. These property enhancements of PS nanocomposites are attributed to the superior dispersion, catalytic and barrier effects of Ti3C2 nanosheets.

Robust, Lightweight, Hydrophobic, and Fire-Retarded Polyimide/MXene Aerogels for Effective Oil/Water Separation.

Polyimide (PI) aerogels have attracted great attention owing to their low density and excellent thermal stability. However, hydrophobic surface modification is required for PI aerogels to improve their ability in oil/water separation due to their amphiphilic characteristic. Two-dimensional MXenes (transition metal carbides/nitrides) can be utilized as nanofillers to enhance the properties of polymers because of their unique layered structure and versatile interface chemistry. Herein, the robust, lightweight, and hydrophobic PI/MXene three-dimensional architectures were fabricated via freeze-drying of polyamide acid/MXene suspensions and thermal imidization. Polyamide acid was synthesized using N-N-dimethylacetamide and 4,4'-oxydianiline. MXene (Ti3C2Tx) dispersion was obtained via the etching of Ti3AlC2 and ultrasonic exfoliation. Taking advantage of the strong interaction between PI chains and MXene nanosheets, the interconnected, highly porous, and hydrophobic PI/MXene aerogels with low density were fabricated, resulting in the improved compressive performance, remarkable oil absorption capacity, and efficient separation of oil and water. For the PI/MXene-3 aerogel (weight ratio, 5.2:1) without any surface modification, the water contact angle was 119° with a density of 23 mg/cm3. This aerogel can completely recover to its original height after 50 compression-release cycles, exhibiting superelasticity and exceptional fatigue-resistant ability. It also showed high absorption capacities to various organic liquids ranging from approximately 18 to 58 times of their own weight. This hybrid aerogel can rapidly separate the chloroform, soybean oil, and liquid paraffin from the water-oil system. The thermally stable hybrid aerogel also exhibited excellent fire safety properties and outstanding reusability under an extreme environment.

Interface decoration of exfoliated MXene ultra-thin nanosheets for fire and smoke suppressions of thermoplastic polyurethane elastomer.

Thermoplastic polyurethane (TPU) has broad applications as lightweight materials due to its multiple advantages and unique properties. Nevertheless, toxicity emission under fire conditions remains a major concern, particularly in building fire scenarios. To circumvent the problem, it is imperative that an effective flame retardant is sought to suppress the flame and release of combustion/smoke products whilst maintaining the favorable material properties of TPU. In the current work, a simple method is proposed for the preparation and utilization of cetyltrimethyl ammonium bromide (CTAB) and tetrabutyl phosphine chloride (TBPC) modified Ti3C2 (MXene) ultra-thin nanosheets. During the cone calorimeter tests, significant reduction in peak heat release rate (51.2% and 52.2%), peak smoke production rate (57.1% and 57.4%), peak CO production (39.4% and 41.6%) and peak CO2 production (49.7% and 51.7%) were recorded by the mere introduction of 2 wt.% CTAB-Ti3C2 and TBPC-Ti3C2 to TPU. These superior fire safety properties resulting from the significant reduction of the fire, smoke and toxicity hazards are attributed to the excellent dispersion, catalytic and barrier effect of Ti3C2 ultra-thin nanosheets in TPU. Future applications of exfoliated MXene nanosheets as flame retardant appear to be very promising.

Surface Manipulation of Thermal-Exfoliated Hexagonal Boron Nitride with Polyaniline for Improving Thermal Stability and Fire Safety Performance of Polymeric Materials.

In this article, the polyaniline (PANI)/thermal-exfoliated hexagonal boron nitride (BNO) hierarchical structure (PANI-BNO) was constructed via in situ deposition to improve the dispersion and interfacial adhesion of boron nitride in multi-aromatic polystyrene (PS) and polar thermoplastic polyurethane (TPU). Because of the conjugated structure and polar groups in PANI, the uniform dispersion and strong interfacial adhesion between PANI-BNO and PS and TPU were achieved. Thermogravimetric analysis results showed that the incorporation of PANI-BNO enhanced the thermal stability of PS and TPU, i.e., the temperatures at both 5 and 50 wt % mass loss. In addition, PANI with high charring ability also acted as a critical component to generate a synergistic effect with BNO on reducing the fire hazards of PS and TPU. This well-designed structure led to a remarkable reduction of flammable decomposed products and CO and CO2 yields. Meanwhile, a dramatic decrease in the real-time smoke density and total smoke production was observed for PS and TPU nanocomposites with 3 wt % PANI-BNO hybrids, respectively. The multiple synergistic effects (synergistic dispersion, char formation, and barrier effect) are believed to be the primary source for these enhanced properties of polymer nanocomposites.

Novel 3D Network Architectured Hybrid Aerogel Comprising Epoxy, Graphene, and Hydroxylated Boron Nitride Nanosheets.

A novel three-dimensional (3D) epoxy/graphene nanosheet/hydroxylated boron nitride (EP/GNS/BNOH) hybrid aerogel was successfully fabricated in this study. This was uniquely achieved by constructing a well-defined and interconnected 3D network architecture. The manufacturing process of EP/GNS/BNOH involved a simple one-pot hydrothermal strategy, followed by the treatment of freeze-drying and high-temperature curing. In comparison with EP/GNS-3, EP/GNS/BNOH-3 demonstrated improvement of 97% for compressive strength at 70% strain. Through compression tests, fracture occurred for EP/GNS-3 at ninth compression cycles, whereas EP/GNS/BNOH-3 retained its original form after twenty compression cycles, with a residual height of 97% (i.e., only 3% reduction). By the addition of BNOH in the polymer matrix, the dynamic heat transfer and dissipation rates of EP/GNS/BNOH aerogels were also considerably reduced, indicating that the aerogel with BNOH additive possessed excellent thermal insulation properties. Thermogravimetric analysis results revealed that the thermal stabilities of EP/GNS and EP/GNS/BNOH aerogels were improved with increasing loading of EP, and EP/GNS/BNOH aerogels exhibited a better thermal stability at high temperatures. Through the elevated levels attained in the compressive strength, superelasticity, and thermal resistance, EP/GNS/BNOH aerogels has the great potential of being a very effective thermal insulation material to be utilized across a board range of applications in building, automotive, spacecraft, and mechanical systems.