Deep learning-based magnetic resonance imaging analysis for chronic cerebral hypoperfusion risk.

BACKGROUND: Chronic cerebral hypoperfusion (CCH) is a frequently encountered clinical condition that poses a diagnostic challenge due to its nonspecific symptoms. PURPOSE: To enhance the diagnosis of CCH and non-CCH through Magnetic Resonance Imaging (MRI), offering support in clinical decision-making and recommendations to ultimately elevate diagnostic accuracy and optimize patient treatment outcomes. METHODS: In the retrospective research, we collected 204 routine brain magnetic resonance imaging (MRI) from March 1 to September 10 2022, as training and testing cohorts. And a validation cohort with 108 samples was collected from November 14 2022 to August 4 2023. MRI sequences were processed to obtain T1-weighted (T1WI) and T2-weighted (T2WI) sequence images for each patient. We propose CCH-Network (CCHNet), an end-to-end deep learning model, integrating convolution and Transformer modules to capture local and global structural information. Our novel adversarial training method improves feature knowledge capture, enhancing both generalization ability and efficiency in predicting CCH risk. We assessed the classification performance of the proposed model CCHNet by comparing it with existing state-of-the-art deep learning algorithms, including ResNet34, DenseNet121, VGG16, Convnext, ViT, Coat, and TransFG. To better validate model performance, we compared the results of the proposed model with eight neurologists to evaluate their consistency. RESULTS: CCHNet achieved an AUC of 91.6% (95% CI: 86.8-99.1), with an accuracy (ACC) of 85.0% (95% CI: 75.6-95.2). It demonstrated a sensitivity (SE) of 80.0% (95% CI: 71.6-95.6) and a specificity (SP) of 90.0% (95% CI: 82.3-97.8) in the testing cohort. In the validation cohort, the model demonstrated an AUC of 86.0% (95% CI: 80.3-93.0), an ACC of 84.2% (95% CI: 70.2-93.6), a SE of 83.3% (95% CI: 68.3-95.5), and a SP of 84.7% (95% CI: 70.3-96.8). CONCLUSIONS: The model improved the diagnostic performance of MRI with high SE and SP, providing a promising method for the diagnosis of CCH.

The cell fate regulator DACH1 modulates ferroptosis through affecting P53/SLC25A37 signaling in fibrotic disease.

BACKGROUND: Dachshund homolog 1 (DACH1) is widely acknowledged for its involvement in regulating diverse cell fates, but its precise regulatory mechanism in ferroptosis remains elusive. In this study, we investigated whether DACH1 modulates ferroptosis through affecting P53/solute carrier family 25 member 37 (SLC25A37) signaling in hepatic fibrogenesis. METHODS: CRISPR-Cas9 system was used to knockout DACH1 in HSC to determine the effect of DACH1 on ferroptosis. Immunoprecipitation, pulldown, and mouse model of hepatic fibrogenesis were used to analyze the potential molecular mechanism of ferroptosis regulation by DACH1. RESULTS: We found that ferroptosis inducers increased the protein expression of DACH1 by suppressing the ubiquitin-proteasome signaling. DACH1 knockout can resist ferroptosis, whereas DACH1 knockin can enhance it. Interestingly, the upregulation of DACH1 resulted in the mitochondrial translocation of p53 by inducing phosphorylation at serine 392. The mutation of serine 392 can prevent the combination of DACH1 and p53, the mitochondrial translocation of p53, and DACH1-mediated ferroptosis. Moreover, SLC25A37 was identified as a candidate target for mitochondrial p53. The binding of p53 to SLC25A37 can enhance the iron uptake capacity of SLC25A37, which may cause an overload of iron in the mitochondria and hyperactive mitochondrial electron transport chain. Knockdown of SLC25A37 can impair p53-mediated mitochondrial iron overload and ferroptosis. Furthermore, treatment with erastin can induce HSC ferroptosis and relieve fibrotic lesion damage in the mouse model of hepatic fibrogenesis. HSC-specific knockdown of DACH1, p53, and SLC25A37 can abolish the induction of HSC ferroptosis and reversal of hepatic fibrogenesis by erastin treatment. CONCLUSIONS: Our findings suggest that the DACH1/P53/SLC25A37 signaling pathway is a promising target for fibrotic disorders and reveals new regulatory mechanisms of ferroptosis.

Integrated single-cell and bulk RNA sequencing reveals CREM is involved in the pathogenesis of ulcerative colitis.

Background: Ulcerative colitis (UC) is an inflammatory bowel disease characterized by persistent colonic inflammation. Here, we performed a systematic analysis to gain better insights into UC pathogenesis. Methods: We analyzed two UC-related datasets extracted from the gene expression omnibus database using several bioinformatics tools. The primary cell types and key subgroups of primary cells associated with UC and differentially expressed genes (DEGs) between UC and control samples were identified. The molecular regulation of the key genes was also predicted. The gene ontology and Kyoto encyclopedia of genes and genomes enrichment analyses of marker genes of key cell subgroups and model genes were performed. The expression of key enriched genes was validated in 10 clinical samples using real-time quantitative polymerase chain reaction (RT-qPCR). Results: Monocytes were identified as the major cell type. Ten differentially expressed marker genes were obtained by intersecting the 3121 DEGs, 38 marker genes in major cell types, and 104 marker genes in key cell subgroups. Four essential genes, associated with immune response, were obtained using support vector machine recursive feature elimination and least absolute shrinkage and selection operator analyses. The four essential genes were highly expressed in Cluster 0 during differentiation. Validation of the four key genes in colonic mucosal biopsy specimens from 10 normal and 10 UC patients revealed that CREM was highly expressed in both the lesion-free sites and lesion sites colonic mucosa of UC patients compared with normal adults. Conclusions: We identified CREM involved in UC pathogenesis, which is expected to provide a new therapeutic target for UC.

Huanglian-banxia promotes gastric motility of diabetic rats by modulating brain-gut neurotransmitters through MAPK signaling pathway.

BACKGROUND: Gastric motility disorder is an increasingly common problem among people with diabetes. Neurotransmitters have been recognized as critical regulators in the process of gastric motility. Previous study has shown that herb pair huanglian-banxia (HL-BX) can improve gastric motility, but the underlying mechanism is still unclear. The aim of this study was to further investigate the role of HL-BX in modulating brain-gut neurotransmission to promote gastric motility in diabetic rats, and to explore its possible mechanism. METHODS: The diabetic rats were divided into five groups. Gastric emptying rate, intestinal propulsion rate, body weight, and average food intake were determined. Substance P (SP), 5- hydroxytryptamine (5-HT), and glucagon-like peptide -1 (GLP-1) in the serum were measured by enzyme-linked immunosorbent assay. Dopamine (DA) and norepinephrine (NE) in the brain were analyzed by high-pressure liquid chromatography with a fluorescence detector. Protein expression of the tissues in the stomach and brain was determined by Western blot. KEY RESULTS: HL-BX reduced average food intake significantly, increased body weight, and improved gastric emptying rate and intestinal propulsion rate. HL-BX administration caused a significant increase in SP, GLP-1, and 5-HT, but a significant decrease in DA and NE. Interestingly, HL-BX regulated simultaneously the different expressions of MAPK and its downstream p70S6K/S6 signaling pathway in the stomach and brain. Moreover, berberine exhibited a similar effect to HL-BX. CONCLUSIONS: These results indicated that HL-BX promoted gastric motility by regulating brain-gut neurotransmitters through the MAPK signaling pathway. HL-BX and MAPK provide a potential therapeutic option for the treatment of gastroparesis.

Predictive Role of Pre-Thrombolytic Neutrophil-Platelet Ratio on Hemorrhagic Transformation After Intravenous Thrombolysis in Acute Ischemic Stroke.

To investigate the predictive role of the neutrophil-platelet ratio (NPR) before intravenous thrombolysis (IVT) on hemorrhagic transformation (HT) in patients with acute ischemic stroke (AIS). AIS patients treated with IVT without endovascular therapy between June 2019 and February 2023 were included. Patients were divided into high NPR (>35) and low NPR (≤35) groups according to the optimal threshold NPR value for identifying high-risk patients before IVT. The baseline data and the incidence of HT and symptomatic intracranial hemorrhage (sICH) were compared between the two groups. The predictive role of the NPR and other related factors on HT after IVT was analyzed by multivariate logistic regression. A total of 247 patients were included, with an average age of 67.5 ± 12.4 years. Post-thrombolytic HT was observed in 18.6% of the patients, and post-thrombolytic sICH was observed in 1.2% of the patients. There were 69 patients in the high NPR group and 178 patients in the low NPR group. The incidence of HT in the high NPR group was significantly higher than that in the low NPR group (30.4% vs 16.3%, P < .05). The incidence of sICH was significantly higher in the high NPR group than in the low NPR group (14.5% vs 1.7%, P < .001). Multivariate logistic regression analysis showed that NPR > 35 was positively correlated with HT (odds ratio (OR) = 3.236, 95% confidence interval (CI): 1.481-7.068, P = .003) and sICH (OR = 13.644, 95% CI: 2.392-77.833, P = .003). A high NPR (>35) before IVT may be a predictor of HT in AIS patients. This finding may help clinicians make clinical decisions before IVT in AIS patients.

The Therapeutic Mechanisms of Shenyan Oral Liquid I Against Chronic Kidney Disease Based on Network Pharmacology and Experimental Validation.

BACKGROUND: Chronic Kidney Disease (CKD) leads to structural and functional abnormalities of the kidneys and seriously jeopardizes human health. Shenyan Oral Liquid (SOLI), a Chinese medicinal preparation, has been reported to protect podocytes in patients with chronic kidney disease (CKD). OBJECTIVE: The objective of this study is to investigate the mechanism of action of the Chinese medicinal preparation Senyan Oral Liquid (SOLI) in the treatment of CKD by protecting podocytes through network pharmacology technology and experimental validation. METHODS: Compounds of SOLI and targets of CKD disease were collected and screened. The SOLI network of bioactive compounds targeting CKD and the protein-protein interaction (PPI) network were constructed using Cytoscape software and the STRING online database. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed using the R software Cluster Profiler package. Molecular docking was performed using Autodock software to verify the binding ability of bioactive compounds and target genes. Subsequently, the potential mechanism of SOLI on CKD predicted by network pharmacological analysis was experimentally studied and verified in an adriamycin-induced nephropathy rat model. RESULTS: A total of 81 targets of SOLI components acting on CKD were identified. The results of the PPI analysis clarified that five key target genes (TNF, AKT1, IL6, VEGFA, and TP53) play a critical role in the treatment of CKD by SOLI. The GO analysis and KEGG enrichment analysis indicated that SOLI acts through multiple pathways, including the PI3K/AKT signaling pathway against CKD. Molecular docking showed that the main compounds of SOLI and five key genes had strong binding affinity. In a rat model of adriamycin-induced nephropathy, SOLI significantly ameliorated disease symptoms and improved renal histopathology. Mechanistic studies showed that SOLI upregulated the expression level of Nephrin, inhibited the PI3K/AKT pathway in renal tissues, and ultimately suppressed the activation of autophagy-related proteins in CKD. CONCLUSION: SOLI exerted a renoprotective effect by regulating the Nephrin-PI3K/AKT autophagy signaling pathway, and these findings provide new ideas for the development of SOLI-based therapeutic approaches for CKD.

Cerebral blood volume index can predict the long-term prognosis after endovascular thrombectomy in patients with acute ischemic stroke due to large vessel occlusion.

Long-term prognosis and factors influencing endovascular therapy (EVT) remain unclear. This study aimed to investigate the association between computed tomography perfusion (CTP) parameters and long-term prognosis of patients with acute ischemic stroke (AIS) treated with EVT. Patients with AIS due to large vessel occlusion treated with EVT were prospectively included for a 1-year follow-up. All patients and their data were grouped based on the hypoperfusion intensity ratio (HIR, ＜0.3 vs. ≥ 0.3) and cerebral blood volume (CBV) index (＞0.7 vs. ≤ 0.7). The primary outcome was favorable prognosis, defined as a modified Rankin Scale (mRS) score of 0-2. Multivariate logistic regression was used to analyze factors influencing long-term favorable prognosis. Of 69 patients included, 35 (50.7 %) achieved mRS 0-2 at one year. A favorable prognosis was observed predominantly in patients with higher CBV index (75.0 % vs. 34.1 %, p= 0.001) and lower HIR (72.0 % vs. 38.6 %, p=0.008). In the multivariate logistic regression, CBV index (odds ratio (OR) = 4.362; 95 % confidence interval (CI): 1.052, 18.082; p = 0.042), baseline National Institutes of Health Stroke Scale (NIHSS) score (OR = 0.913; 95 % CI: 0.836, 0.997; p = 0.044), and symptomatic intracranial hemorrhage (sICH) (OR = 0.089; 95 % CI: 0.009, 0.925; p = 0.043) were independently associated with a long-term favorable prognosis. The CBV index may serve as a predictor of the long-term prognosis of patients treated with EVT. The novel finding is that the baseline NIHSS score and sICH were associated with long-term prognosis.

Direct Thrombectomy versus Bridging Thrombectomy within 6 Hours of Stroke Onset: A Prospective Cohort Study on Cognitive and Physical Function Outcomes.

PURPOSE: To evaluate the physical and cognitive functions of patients with stroke who underwent either direct or bridging thrombectomy within 6 hours of stroke onset. MATERIALS AND METHODS: Patients with large vessel occlusion in anterior circulation treated with direct (direct group) or bridging thrombectomy (bridging group) were prospectively analyzed between June 2020 and February 2022. The efficacy outcome was the 3-month modified Rankin Scale (mRS) score, the safety outcome was symptomatic intracranial hemorrhage (sICH), and cognitive function was assessed using the Clinical Dementia Rating (CDR) scale at 6 months after stroke. RESULTS: A total of 125 patients (direct group, n = 75; bridging group, n = 50) who had completed follow-up at 3 months by telephone call were included. No significant differences were observed between the direct and bridging groups in terms of an mRS score of 0-2 (25.3% vs 22.0%, respectively; P = .83), an mRS score of 0-3 (37.3% vs 44.0%, respectively; P = .58), sICH (17.3% vs 14.0%, respectively; P = .80), or 3-month all-cause mortality (36.3% vs 30.0%, respectively; P = .34). Sixty-nine patients (direct group, n = 38; bridging group, n = 31) completed the CDR assessment at 6 months after stroke. There was no significant difference in poststroke dementia, defined as a CDR score of ≥1 point between the direct group (42.1%) and bridging group (22.6%) (P = .12). Ordinal regression analyses showed that the CDR score at 6 months was not associated with treatment type (direct thrombectomy vs bridging thrombectomy). CONCLUSIONS: With regard to physical and cognitive functions at 3 and 6 months, direct thrombectomy was comparable with bridging thrombectomy in patients who were treated within 6 hours of stroke onset.

Predictive role of pre-thrombolytic hs-CRP on the safety and efficacy of intravenous thrombolysis in acute ischemic stroke.

PURPOSE: To investigate the predictive role of pre-thrombolytic high sensitivity C-reactive protein (hs-CRP) on the safety and efficacy of intravenous thrombolysis in patients with acute ischemic stroke (AIS). METHODS: Patients with AIS who underwent intravenous thrombolysis with recombinant plasminogen activator (rtPA) or urokinase without endovascular therapy from June 2019 to June 2022 were retrospectively analysed. All patients were grouped into two groups (high or low hs-CRP group) according to the median value of hs-CRP before intravenous thrombolysis. The baseline NIHSS, NIHSS changes before and after thrombolysis (ΔNIHSS), the rate of good thrombolysis response (NIHSS decreased ≥ 2 points from baseline), the rate of any intracranial hemorrhage, age, sex, hypertension, diabetes, uric acid and platelet count were compared between the two groups. Logistic regression analysis was performed to identify possible prognostic factors for a good thrombolysis response. RESULTS: A total of 212 patients were included in the analysis, with a mean age of 66.3 ± 12.5 years. In total, 145 patients received rtPA, and 67 patients received urokinase. Patients were divided into a high hs-CRP group (> 1.60 mg/L) and a low hs-CRP group (≤ 1.60 mg/L) according to the median hs-CRP level (1.60 mg/L). The ΔNIHSS of the high hs-CRP group was significantly smaller than that of the low hs-CRP group (0 [-1 ~ 0] vs. -1 [-2 ~ 0], P < 0.05). The good rate of thrombolysis response in the high hs-CRP group was significantly lower than that in the low hs-CRP group (21.9% vs. 36.5%, P < 0.05). Similar results were shown in the rtPA subgroup between the high and low hs-CRP groups but not in the urokinase subgroup. Logistic regression analysis showed that hs-CRP > 1.60 mg/L was negatively correlated with a good thrombolysis response rate (OR = 0.496, 95% CI = 0.266-0.927, P = 0.028). CONCLUSION: hs-CRP > 1.6 mg/L may serve as a poor prognosis predictive factor for patients with AIS receiving intravenous thrombolysis. However, due to the small sample size of this study, further studies are needed to verify our results.

Honokiol inhibits interleukin-induced angiogenesis in the NSCLC microenvironment through the NF-κB signaling pathway.

Tumor angiogenesis, which may be affected by microenvironmental inflammation and promotes tumor development and metastasis, is one of the key reasons contributing to increased mortality. The goal of this study is to investigate how lignin analogs, specifically honokiol (HNK), block angiogenesis induced by the inflammatory milieu of lung cancer. The human lung cancer cell lines A549 and H460 were treated with HNK. Interleukin-1 was employed to mimic an inflammatory tumor microenvironment. Findings demonstrated that HNK drastically decreased the cell viability of A549 and H460 cells. In A549 and H460 cells, HNK also reduced the production of vascular endothelial growth factor (VEGF), the most important marker of tumor angiogenesis. Signal pathway studies revealed that HNK blocked the NF-κB signaling pathway. This effect, in turn, prevented the expression of VEGF by inhibiting the NF-κB signaling pathway. Human umbilical vein endothelial cells (HUVECs) from A549-conditioned medium cultures were subjected to HNK treatment, which decreased tubulogenesis, horizontal and vertical migration, and cell proliferation in HUVECs. Overall, HNK inhibited the NF-κB pathway. This effect resulted in the downregulation of VEGF, thus reducing the viability and angiogenesis of human lung cancer cell lines. In A549 cell xenografts, HNK decreased VEGF expression, tumor angiogenesis, and tumor development. Our research shows that HNK is a potential antiangiogenic molecule for the treatment of lung cancer.

Purinergic signaling: a potential therapeutic target for ischemic stroke.

Pathogenesis of ischemic stroke is mainly characterized by thrombosis and neuroinflammation. Purinergic signaling pathway constitutes adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), and adenosine (ADO). ATP is hydrolyzed to ADP and then to AMP by extracellular nucleotidase CD39; AMP is subsequently converted to adenosine by CD73. All these nucleotides and nucleosides act on purinergic receptors protecting against thrombosis and inhibit inflammation. In addition, many physical methods have been found to play a neuroprotective role through purinergic signaling. This review mainly introduces the role and potential mechanism of purinergic signalings in the treatment of ischemic stroke, so as to provide reference for seeking new treatment methods for stroke.

Local buckling behavior of buried pipeline under seismic oblique-reverse fault displacement.

Seismic fault displacement is the main factor leading to local buckling failure of the buried pipeline, especially crossing the oblique-reverse fault. The local buckling behavior of the buried pipeline is complex under the 3-D displacement of the oblique-reverse fault. In this work, the pipe local buckling mechanism was discussed, then a shell and solid element nonlinear contact coupling model of the pipeline crossing oblique-reverse fault was established based on the ABAQUS program. The local buckling behavior (potential local buckling locations, developing process) of the pipeline under oblique-reverse fault displacement was systematically analyzed, comparing against the same under single fault displacement. Subsequently, the influence of internal pressure, diameter thickness ratio and burial depth on the local buckling behavior of the pipeline were discussed. The numerical results revealed two potential locations and three stages of the local buckling, then the potential local buckling locations and three stages of the local buckling under different internal pressure, diameter thickness ratio and burial depth were obtained. It proves that the local buckling of the pipeline is more sensitive to the oblique-reverse fault displacement than single fault displacement and provides a reference for the aseismic design and reinforcement of the pipeline crossing the oblique-reverse fault.

Continuous current-injected waveforms shaping for suppressing relaxation oscillations of direct modulation based on equivalent circuit model.

An improved technique of continuous shaping current-injected waveforms based on the single-mode rate equations is proposed to suppress relaxation oscillations (ROs) from direct modulation of distributed feedback laser (DFB). The signal expression of shaping current is deduced theoretically from the dependence of DFB desired output waveforms in detail, and the specific parameters derivation of the different polynomial degree is also discussed necessarily. Furthermore, a polynomial p-function with inverse operation is adopted to construct the Fourier series corresponding to injection current waveform signal. The equivalent circuit model with DFB phenomenological description is injected into shaping current signal to verity the proposed validity by evaluating the static and dynamic characteristics. The simulation results of the optimized shaping signal show the good agreement with the desired output pulse including rising and falling edge and suppress the ROs amplitude dramatically at the two jump edges.

Huangkui lianchang decoction attenuates experimental colitis by inhibiting the NF-κB pathway and autophagy.

Ulcerative colitis (UC) is a chronic inflammatory colorectal disease characterized by excessive mucosal immune response activation and dysfunction of autophagy in intestinal epithelial cells. Traditional herbal preparations, including the Huangkui lianchang decoction (HLD), are effective in UC clinical treatment in East Asia, but the underlying mechanism is unclear. This study evaluated the therapeutic effects and associated molecular mechanisms of HLD in UC in vivo and in vitro. A C57BL/6 UC mouse model was established using 2.5% dextran sulfate sodium. The effects of HLD on the colonic structure and inflammation in mice were evaluated using mesalazine as the control. The anti-inflammatory effects of HLD were assessed using disease activity index (DAI) scores, histological scores, enzyme-linked immunosorbent assay, immunohistochemistry, immunofluorescence, and western blotting. HLD displayed a protective effect in UC mice by reducing the DAI and colonic histological scores, as well as levels of inflammatory cytokines and NF-κB p65 in colonic tissues. NCM460 lipopolysaccharide-induced cells were administered drug serum-containing HLD (HLD-DS) to evaluate the protective effect against UC and the effect on autophagy. HLD-DS exhibited anti-inflammatory effects in NCM460 cells by reducing the levels of inflammatory cytokines and increasing interleukin 10 levels. HLD-DS reduced p-NF-κB p65, LC3II/I, and Beclin 1 expression, which suggested that HLD alleviated colitis by inhibiting the NF-κB pathway and autophagy. However, there was no crosstalk between the NF-κB pathway and autophagy. These findings confirmed that HLD was an effective herbal preparation for the treatment of UC.

Cerebral blood volume index may be a predictor of independent outcome of thrombectomy in stroke patients with low ASPECTS.

INTRODUCTION: To evaluate the predictors for efficacy and safety of patients with acute ischemic stroke (AIS) and Alberta Stroke Program Early Computed Tomographic Score (ASPECTS) ＜6 undergoing endovascular therapy (EVT). METHODS: This study retrospectively analyzed consecutive patients presented between December 2020 and December 2021 with large vessel occlusions (LVO) within the anterior circulation and an ASPECTS ＜6, followed by EVT. The efficacy outcome was 90-day functional independence, defined as modified Rankin Scale (mRS) score 0-3. The primary safety outcome was symptomatic intracranial hemorrhage (sICH). Secondary safety outcomes included 90-day all-cause mortality and 24-hour any ICH. RESULTS: A total of 22 patients were included. The percentage of patients with mRS 0-3 at 90 days was 36.4% (8/22). The occurrence of sICH was 22.7% (5/22). The occurrence of any ICH was 45.5% (10/22). The 90-day all-cause mortality was 36.4% (8/22). Median (interquartile range, IQR) cerebral blood volume (CBV) index was 0.5 (0.4-0.7). CBV index in mRS 0-3 group (n = 8) was higher than mRS 4-5 group (n = 14) (P＜0.05). There was no significant difference of age, gender, comorbidities, baseline National Institutes of Health Stroke Scale (NIHSS) score, mismatch ratio, CBV index, interval between stroke onset and re-perfusion, good re-perfusion rate between sICH group (n = 5) and non-sICH group (n = 17). CONCLUSIONS: AIS patients with low ASPECTS can still benefit from EVT and gain good functional outcome, especial those had higher CBV index on pre-EVT computed tomography perfusion (CTP). Further studies with larger sample size are needed to validate our findings.

Implementing an Air Suction Effect Induction Strategy to Create Super Thermally Insulating and Superelastic SiC Aerogels.

Silicon carbide (SiC) aerogels are promising thermal insulators that are lightweight and possess high thermal stability. However, their application is hindered by their brittleness. Herein, an air suction effect induction (ASEI) strategy is proposed to fabricate a super thermally insulating SiC aerogel (STISA). The ASEI strategy exploits the air suction effect to subtly regulate the directional flow of the SiO gas, which can induce directional growth and assembly of SiC nanowires to form a directional lamellar structure. The sintering time is significantly reduced by >90%. Significant improvements in the compression and elasticity performance of the STISA are achieved upon the formation of a directional lamellar structure through the ASEI strategy. Moreover, the lamellar structure endows the STISA with an ultralow thermal conductivity of 0.019 W m-1 K-1 . The ASEI strategy paves the way for structural design of advanced ceramic aerogels for super thermal insulation.

Improvement of the Thermal Insulation Performance of Silica Aerogel by Proper Heat Treatment: Microporous Structures Changes and Pyrolysis Mechanism.

A simple heat treatment method was used to optimize the three-dimensional network structure of the hydrophobic aerogel, and during the heat treatment process at 200-1000 °C, the thermal conductivity of the aerogel reached the lowest to 0.02240 W/m·K between 250 °C and 300 °C, which was mainly due to the optimization of microstructure and pyrolysis of surface groups. Further Fluent heat-transfer simulation also confirmed the above results. Synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) was used to finely measure the pyrolysis process of aerogels, and the pyrolysis process of aerogel was divided into four stages. (I) Until 419 °C, as the temperature continued to rise, surface methyl groups were oxidized to form hydroxyl. (II) As the temperature reached to 232 °C, the oxidation proceeded. In addition, inside the aerogel, because of lacking oxygen, the reaction produced CH4 and C-Si bonds would form. (III) After 283 °C, Si-OH groups began to condense to form Si-O-Si, which optimized the three-dimensional network structures to be beneficial to improve the thermal insulation performance of silica aerogel. (IV) When it reached 547 °C, the chemical reaction was terminated, and all the primary particles gradually fused into secondary particles and sintered to form clusters.

"Robust-Soft" Anisotropic Nanofibrillated Cellulose Aerogels with Superior Mechanical, Flame-Retardant, and Thermal Insulating Properties.

Advanced thermal insulation materials with low thermal conductivity and robustness derived from regenerative resources are badly needed for building energy conservation. Among them, nanofibrillated cellulose aerogels have huge application potential in the field of thermal insulation materials, but it is still a challenge to prepare cellulose aerogels of excellent comprehensive properties in a simple way. Herein, we demonstrate a unidirectional freeze-drying strategy to develop a novel "robust-soft" anisotropic nanofibrillated cellulose aerogel (NFC-Si-T) by integrating nanofibrillated cellulose (NFC) and Si-O-Si bonding networks under the catalytic dehydration of p-toluenesulfonic acid (TsOH). The anisotropic structure endows the NFC-Si-T with high flexibility that can be easily bent or even tied with a knot, and in addition, it possesses high Young's modulus (1-3.66 MPa) that can resist the compression weight of 10,000 times of its own weight without deformation. Furthermore, the NFC-Si-T aerogels exhibit anisotropic thermal insulation performances with a low average thermal conductivity (0.028-0.049 W m-1 K-1). More importantly, the limited oxygen index of the NFC-Si-T reaches up to 42.6-51%, showing excellent flame-retardant performance. Therefore, the "robust-soft" anisotropic NFC-Si-T aerogels can be used as an advanced thermal insulation material for building thermal insulation applications.

Novel Red Light-Absorbing Organic Dyes Based on Indolo[3,2-b]carbazole as the Donor Applied in Co-Sensitizer-Free Dye-Sensitized Solar Cells.

Three novel organic dyes (D6, D7 and D8), based on indolo[3,2-b]carbazole as the donor and different types of electron-withdrawing groups as the acceptors, were synthesized and successfully applied in dye-sensitized solar cells (DSSCs). Their molecular structures were fully characterized by 1H NMR, 13C NMR and mass spectroscopy. The density functional theory (DFT) calculations, electrochemical impedance spectroscopy analysis, UV-Vis absorption characterization and tests of the solar cells were used to investigate the photophysical/electrochemical properties as well as DSSCs' performances based on the dyes. Dye D8 showed the broadest light-response range (300-770 nm) in the incident monochromatic photo-to-electron conversion efficiency (IPCE) curve, due to its narrow bandgap (1.95 eV). However, dye D6 exhibited the best device performance among the three dyes, with power conversion efficiency of 5.41%, Jsc of 12.55 mA cm-2, Voc of 745 mV and fill factor (FF) of 0.59. We also found that dye aggregation was efficiently suppressed by the introduction of alkylated indolo[3,2-b]carbazole, and, hence, better power conversion efficiencies were observed for all the three dyes, compared to the devices of co-sensitization with chenodeoxycholic acid (CDCA). It was unnecessary to add adsorbents to suppress the dye aggregation.

Mechanically strong polyimide aerogels cross-linked with low-cost polymers.

Polyimide aerogels were prepared using low-cost polymers with different structure capped polyamide oligomers serving as cross-linking agents. To investigate the effects of the anhydride density on cross-linker chain units and side groups of cross-linkers on their properties and microstructures, two kinds of polymers from maleic anhydride, endic anhydride, and styrene were prepared by simple radical polymerization. The polyimide aerogels exhibit densities as low as 0.087 g cm-3 and specific surface areas as high as 456 m2 g-1. And the maximum modulus of the aerogel is up to 21.3 MPa. These cross-linkers are alternatives to expensive small molecule cross-linkers, therefore reducing the cost of PI aerogels.