Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 17 de 17
Filter
1.
Adv Mater ; : e2403296, 2024 Apr 11.
Article in English | MEDLINE | ID: mdl-38602707

ABSTRACT

Combining immune checkpoint blockade with chemotherapy through nanotechnology is promising in terms of safety and efficacy. However, the distinct subcellular distribution of each ingredient's action site makes it challenging to acquire an optimal synergism. Herein, a dual-pH responsive hybrid polymeric micelle system, HNP(αPDL16.9, Dox5.3), is constructed as a proof-of-concept for the spatial cooperativity in chemo-immunotherapy. HNP retains the inherent pH-transition of each polymer, with stepwise disassembly under discrete pH thresholds. Within weakly acidic extracellular tumor environment, αPDL1 is first released to block the checkpoint on cell membranes. The remaining intact Doxorubicin-loaded micelle NP(Dox)5.3 displays significant tropism toward tumor cells and releases Dox upon lysosomal pH for efficient tumor immunogenic cell death without immune toxicity. This sequential-released pattern boosts DC activation and primes CD8+ T cells, leading to enhanced therapeutic performance than single agent or an inverse-ordered combination in multiple murine tumor models. Using HNP, the indispensable role of conventional type 1 DC (cDC1) is identified in chemo-immunotherapy. A co-signature of cDC1 and CD8 correlates with cancer patient survival after neoadjuvant Pembrolizumab plus chemotherapy in clinic. This study highlights spatial cooperativity of chemo- and immuno-agents in immunoregulation and provides insights into the rational design of drug combination for future nanotherapeutics development.

2.
Analyst ; 149(4): 1271-1279, 2024 Feb 12.
Article in English | MEDLINE | ID: mdl-38226548

ABSTRACT

T4 polynucleotide kinase helps with DNA recombination and repair. In this study, an electrochemical biosensor was developed for a T4 polynucleotide kinase activity assay and inhibitor screening based on phosphate pillar[5]arene and multi-walled carbon nanotube nanocomposites. The water-soluble pillar[5]arene was employed as the host to complex thionine guest molecules. The substrate DNA with a 5'-hydroxyl group initially self-assembled on the gold electrode surface through chemical adsorption of the thiol group, which was phosphorylated in the presence of T4 polynucleotide kinase. Titanium dioxide nanoparticles served as a bridge to link phosphorylated DNA and phosphate pillar[5]arene and multi-walled carbon nanotube composite due to strong phosphate-Ti4+-phosphate chemistry. Through supramolecular host-guest recognition, thionine molecules were able to penetrate the pillar[5]arene cavity, resulting in an enhanced electrochemical response signal. The electrochemical signal is proportional to the T4 polynucleotide kinase concentration in the range of 10-5 to 15 U mL-1 with a detection limit of 5 × 10-6 U mL-1. It was also effective in measuring HeLa cell lysate-related T4 polynucleotide kinase activity and inhibitor screening. The proposed method offers a unique sensing platform for kinase activity measurement, holding great potential in nucleotide kinase-target drug development, clinical diagnostics, and inhibitor screening.


Subject(s)
Biosensing Techniques , Nanotubes, Carbon , Phenothiazines , Humans , Polynucleotide 5'-Hydroxyl-Kinase , Nanotubes, Carbon/chemistry , Phosphates , HeLa Cells , DNA/chemistry , Biosensing Techniques/methods
3.
ACS Appl Mater Interfaces ; 15(42): 49116-49122, 2023 Oct 25.
Article in English | MEDLINE | ID: mdl-37815493

ABSTRACT

In recent years, functional electrolyte additives have been widely studied during the CO2 evolution reaction (CO2ER) and CO2 reduction reaction (CO2RR) processes for Li-CO2 batteries. Owing to different concerns, functions of these additives are also multiple and limited. In this work, the multiple impacts of functional electrolyte additives for Li-CO2 batteries are discussed. N-phenylpyrrolidine (PPD) and 1-(3-bromophenyl) pyrrole (Br-PPD) are investigated as additives successively. First, the corresponding charging potential during the CO2ER process can be reduced to 3.65 V with PPD; then the Li||Li symmetric cells with Br-PPD possess a superior long-term cycling of 800 h benefited from a stable solid electrolyte interphase (SEI) on the surface of a Li metal by using a Li anode protected with bromine functional groups. In Br-PPD-based Li-CO2 cells, the charging potential can be maintained at 3.70 V for 120 cycles even with a Super P cathode. In this work, the relationship between the structural properties of organic molecules and their electrochemical applications is discussed and investigated. This is essential for the targeted design and preparation of additives in rechargeable batteries.

4.
Cell Rep ; 42(6): 112518, 2023 06 27.
Article in English | MEDLINE | ID: mdl-37210726

ABSTRACT

Bacterial cells were long thought to be "bags of enzymes" with minimal internal structures. In recent years, membrane-less organelles formed by liquid-liquid phase separation (LLPS) of proteins or nucleic acids have been found to be involved in many important biological processes, although most of them were studied on eukaryotic cells. Here, we report that NikR, a bacterial nickel-responsive regulatory protein, exhibits LLPS both in solution and inside cells. Analyses of cellular nickel uptake and cell growth of E. coli confirm that LLPS enhances the regulatory function of NikR, while disruption of LLPS in cells promotes the expression of nickel transporter (nik) genes, which are negatively regulated by NikR. Mechanistic study shows that Ni(II) ions induces the accumulation of nik promoter DNA into the condensates formed by NikR. This result suggests that the formation of membrane-less compartments can be a regulatory mechanism of metal transporter proteins in bacterial cells.


Subject(s)
Escherichia coli Proteins , Escherichia coli , Escherichia coli/metabolism , Escherichia coli Proteins/metabolism , Repressor Proteins/metabolism , Nickel/chemistry , Nickel/metabolism , Bacterial Proteins/metabolism
5.
Front Public Health ; 10: 979649, 2022.
Article in English | MEDLINE | ID: mdl-36033779

ABSTRACT

Introduction: Vitamin K (VK) as a nutrient, is a cofactor in the carboxylation of osteocalcin (OC), which can bind with hydroxyapatite to promote bone mineralization and increase bone strength. However, some studies have been inconsistent on whether vitamin K2 (VK2) can maintain or improve bone mineral density (BMD) and reduce the incidence of fractures in postmenopausal women. Therefore, the main objective of this meta-analysis was to determine the effect of VK2 as a nutritional supplement on BMD and fracture incidence in postmenopausal women. Methods: We searched PubMed, EMBASE, and Cochrane Library databases (published before March 17, 2022) and then extracted and pooled data from all randomized controlled trials (RCTs) that met the inclusion criteria. Results: Sixteen RCTs with a total of 6,425 subjects were included in this meta-analysis. The overall effect test of 10 studies showed a significant improvement in lumbar spine BMD (BMD LS) (P = 0.006) with VK2. The subgroup analysis of VK2 combination therapy showed that BMD LS was significantly maintained and improved with the administration of VK2 (P = 0.03). The overall effect test of the six RCTs showed no significant difference in fracture incidence between the two groups (RR=0.96, P=0.65). However, after excluding one heterogeneous study, the overall effect test showed a significant reduction in fracture incidence with VK2 (RR = 0.43, P = 0.01). In addition, this meta-analysis showed that VK2 reduced serum undercarboxylated osteocalcin (uc-OC) levels and the ratio of uc-OC to cOC in both subgroups of VK2 combined intervention and alone. However, for carboxylated osteocalcin (cOC), both subgroup analysis and overall effect test showed no significant effect of VK2 on it. And the pooled analysis of adverse reactions showed no significant difference between the VK2 and control groups (RR = 1.03, 95%CI 0.87 to 1.21, P = 0.76). Conclusions: The results of this meta-analysis seem to indicate that VK2 supplementation has a positive effect on the maintenance and improvement of BMD LS in postmenopausal women, and it can also reduce the fracture incidence, serum uc-OC levels and the ratio of uc-OC to cOC. In conclusion, VK2 can indirectly promote bone mineralization and increase bone strength.


Subject(s)
Bone Density Conservation Agents , Osteoporosis, Postmenopausal , Female , Humans , Osteocalcin , Randomized Controlled Trials as Topic , Vitamin K 2
6.
J Oncol ; 2022: 1516946, 2022.
Article in English | MEDLINE | ID: mdl-35479964

ABSTRACT

Background: Studies of prognosis-related molecular markers are an important tool to uncover the mechanism of tumour metastasis. Cancer susceptibility gene testing is an important tool for genetic counselling of cancer risk. However, the impact of lung cancer susceptibility genes (LCSGs) on lung cancer metastasis and prognosis has not been well studied. Methods: The list of lung cancer susceptibility genes was retrospectively analysed and updated. After expression profiling and functional analysis, LCSG-based signatures for prognosis were identified by Cox regression and LASSO regression analyses. For translational purposes, nomograms integrating LCSGs and clinical characteristics were constructed. Results: A total of 301 LCSGs were employed for modelling. For lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC), 10-gene and 7-gene signatures were created and independently validated. The LCSG-based risk score could stratify LUAD survival (univariate: hazard ratio (HR) = 1.076, 95% confidence interval (CI) = 1.049-1.103, P < 0.001; multivariate: HR = 1.066, 95% CI = 1.037-1.095, P < 0.001) and LUSC survival (univariate: HR = 1.149, 95% CI = 1.066-1.239, P < 0.001; multivariate: HR = 1.129, 95% CI = 1.038-1.228, P = 0.005). One of the processes affected by differentially expressed genes in both LUAD and LUSC was the negative regulation of epithelial cell differentiation. Conclusions: Overall, novel LCSG-based gene signatures for LUAD and LUSC were constructed. These findings could expand the understanding of the impact of LCSG expression on cancer metastasis and prognosis.

7.
Inf Process Manag ; 59(1): 102796, 2022 Jan.
Article in English | MEDLINE | ID: mdl-34744256

ABSTRACT

In the period of Corona Virus Disease 2019 (COVID-19), millions of people participate in the discussion of COVID-19 on the Internet, which can easily trigger public opinion and threaten social stability. This paper creatively proposes a multi-stage risk grading model of Internet public opinion for public health emergencies. On the basis of general public opinion risk grading analysis, the model continuously pays attention to the risk level of Internet public opinion based on the time scale of regular or major information updates. This model combines Analytic Hierarchy Process Sort II (AHPSort II) and Swing Weighting (SW) methods and proposes a new Multi-Criteria Decision Making (MCDM) method - AHPSort II-SW. Intuitionistic fuzzy number and linguistic fuzzy number are introduced into the model to evaluate the criteria that cannot be quantified. The multi-stage model is tested using more than 2,000 textual data about COVID-19 collected from Microblog, a leading social media platform in China. Seven public opinion risk assessments were conducted from January 23 to April 8, 2020. The empirical results show that in the early COVID-19 outbreak, the risk of public opinion is more serious on macroscopic view. In details, the risk of public opinion decreases slowly with time, but the emergence of important events may still increase the risk of public opinion. The analysis results are in line with the actual situation and verify the effectiveness of the method. Comparative analysis indicates the improved method is proved to be superior and effective, sensitivity analysis confirms its stability. Finally, management suggestions was provided, this study contributes to the literature on public opinion risk assessment and provides implications for practice.

8.
Optom Vis Sci ; 98(9): 1094-1103, 2021 09 01.
Article in English | MEDLINE | ID: mdl-34469930

ABSTRACT

SIGNIFICANCE: Quantifying meibomian gland morphology from meibography images is used for the diagnosis, treatment, and management of meibomian gland dysfunction in clinics. A novel and automated method is described for quantifying meibomian gland morphology from meibography images. PURPOSE: Meibomian gland morphological abnormality is a common clinical sign of meibomian gland dysfunction, yet there exist no automated methods that provide standard quantifications of morphological features for individual glands. This study introduces an automated artificial intelligence approach to segmenting individual meibomian gland regions in infrared meibography images and analyzing their morphological features. METHODS: A total of 1443 meibography images were collected and annotated. The dataset was then divided into development and evaluation sets. The development set was used to train and tune deep learning models for segmenting glands and identifying ghost glands from images, whereas the evaluation set was used to evaluate the performance of the model. The gland segmentations were further used to analyze individual gland features, including gland local contrast, length, width, and tortuosity. RESULTS: A total of 1039 meibography images (including 486 upper and 553 lower eyelids) were used for training and tuning the deep learning model, whereas the remaining 404 images (including 203 upper and 201 lower eyelids) were used for evaluations. The algorithm on average achieved 63% mean intersection over union in segmenting glands, and 84.4% sensitivity and 71.7% specificity in identifying ghost glands. Morphological features of each gland were also fed to a support vector machine for analyzing their associations with ghost glands. Analysis of model coefficients indicated that low gland local contrast was the primary indicator for ghost glands. CONCLUSIONS: The proposed approach can automatically segment individual meibomian glands in infrared meibography images, identify ghost glands, and quantitatively analyze gland morphological features.


Subject(s)
Eyelid Diseases , Meibomian Gland Dysfunction , Algorithms , Artificial Intelligence , Humans , Meibomian Glands/diagnostic imaging , Specimen Handling , Tears
9.
R Soc Open Sci ; 8(8): 210392, 2021 Aug.
Article in English | MEDLINE | ID: mdl-34430044

ABSTRACT

A significant proportion of the adult population worldwide suffers from cerebral aneurysms. If left untreated, aneurysms may rupture and lead to fatal massive internal bleeding. On the other hand, treatment of aneurysms also involve significant risks. It is desirable, therefore, to have an objective tool that can be used to predict the risk of rupture and assist in surgical decision for operating on the aneurysms. Currently, such decisions are made mostly based on medical expertise of the healthcare team. In this paper, we investigate the possibility of using machine learning algorithms to predict rupture risk of vertebral artery fusiform aneurysms based on geometric features of the blood vessels surrounding but excluding the aneurysm. For each of the aneurysm images (12 ruptured and 25 unruptured), the vessel is segmented into distal and proximal parts by cross-sectional area and 382 non-aneurysm-related geometric features extracted. The decision tree model using two of the features (standard deviation of eccentricity of proximal vessel, and diameter at the distal endpoint) achieved 83.8% classification accuracy. Additionally, with support vector machine and logistic regression, we also achieved 83.8% accuracy with another set of two features (ratio of mean curvature between distal and proximal parts, and diameter at the distal endpoint). Combining the aforementioned three features with integration of curvature of proximal vessel and also ratio of mean cross-sectional area between distal and proximal parts, these models achieve an impressive 94.6% accuracy. These results strongly suggest the usefulness of geometric features in predicting the risk of rupture.

10.
Braz J Med Biol Res ; 53(12): e9317, 2020.
Article in English | MEDLINE | ID: mdl-33111744

ABSTRACT

LINC00355 has been reported aberrantly over-expressed and associated with poor prognosis in various types of cancer. However, reports regarding the effect of LINC00355 on lung squamous cell carcinoma (SCC) are rare. This study aimed to explore the function of LINC00355 in the development and progression of lung SCC and reveal the underlying mechanism. The expression and subcellular location of LINC00355 were determined by qRT-PCR and RNA-FISH, respectively. The lung SCC cell growth was analyzed by CCK-8 assay, transwell invasion, wound healing, colony formation, and flow cytometry assays. Reactive oxygen species level was evaluated by DCFH-DA probes. Bioinformatics online websites, luciferase reporter assay, RNA binding protein immunoprecipitation (RIP), and RNA pull-down assays were utilized to investigate the interaction among LINC00355, miR-466, and Ly-1 antibody reactive clone (LYAR). The results showed that LINC00355 was upregulated in lung SCC and was positively associated with poor overall survival in lung SCC patients. LINC00355 was mainly located in the cytoplasm of SCC cells. Additionally, LINC0035 functioned as a competing endogenous RNA (ceRNA) to target miR-466, and LYAR was identified as a direct target of miR-466. LINC00355 expression negatively correlated with miR-466 level, and positively correlated with LYAR level. Mechanistically, knockdown of LINC00355 inhibited cell proliferation, migration and invasion, promoted cell apoptosis in vitro, and suppressed tumor growth in vivo through targeting miR-466, and thus down-regulated LYAR expression. These findings provide a new sight for understanding the molecular mechanism of lung SCC and indicate that LINC00355 may serve as a potential biomarker for the diagnosis and treatment of lung SCC.


Subject(s)
Carcinoma, Squamous Cell , Lung Neoplasms , RNA, Long Noncoding/genetics , Carcinoma, Squamous Cell/genetics , Cell Line, Tumor , Clone Cells , DNA-Binding Proteins , Gene Expression Regulation, Neoplastic , Humans , Lung , Lung Neoplasms/genetics , MicroRNAs , Nuclear Proteins
11.
World J Surg Oncol ; 18(1): 249, 2020 Sep 19.
Article in English | MEDLINE | ID: mdl-32950055

ABSTRACT

BACKGROUND: Integrating phenotypic and genotypic information to improve prognostic prediction is under active investigation for lung adenocarcinoma (LUAD). In this study, we developed a new prognostic model for event-free survival (EFS) and recurrence-free survival (RFS) based on the combination of clinicopathologic variables, gene expression, and mutation data. METHODS: We enrolled a total of 408 patients from the Cancer Genome Atlas Lung Adenocarcinoma (TCGA-LUAD) project for the study. We pre-selected gene expression or mutation features and constructed 14 different input feature sets for predictive model development. We assessed model performance with multiple evaluation metrics including the distribution of C-index on testing dataset, risk score significance, and time-dependent AUC under competing risks scenario. We stratified patients into higher- and lower-risk subgroups by the final risk score and further investigated underlying immune phenotyping variations associated with the differential risk. RESULTS: The model integrating all three types of data achieved the best prediction performance. The resultant risk score provided a higher-resolution risk stratification than other models within pathologically defined subgroups. The score could account for extra EFS-related variations that were not captured by clinicopathologic scores. Being validated for RFS prediction under a competing risks modeling framework, the score achieved a significantly higher time-dependent AUC as compared to that of the conventional clinicopathologic variables-based model (0.772 vs. 0.646, p value < 0.001). The higher-risk patients were characterized with transcriptional aberrations of multiple immune-related genes, and a significant depletion of mast cells and natural killer cells. CONCLUSIONS: We developed a novel prognostic risk score with improved prediction accuracy, using clinicopathologic variables, gene expression and mutation profiles as input, for LUAD. Such score was a significant predictor of both EFS and RFS. TRIAL REGISTRATION: This study was based on public open data from TCGA and hence the study objects were retrospectively registered.


Subject(s)
Adenocarcinoma of Lung , Lung Neoplasms , Adenocarcinoma of Lung/genetics , Gene Expression , Humans , Lung Neoplasms/genetics , Mutation , Prognosis
12.
Front Pharmacol ; 11: 178, 2020.
Article in English | MEDLINE | ID: mdl-32180726

ABSTRACT

Lung cancer remains a leading cause of cancer-associated mortality worldwide, however, molecular mechanisms underlying lung cancer tumorigenesis and progression remain unknown. Here, we report evidence showing that one member of the mammalian methyltransferase-like family (METTL), METTL7B, is a potential molecular target for treatment of non-small cell lung cancer (NSCLC). METTL7B expression was elevated in the majority of NSCLC comparing to normal tissues. Increased expression of METTL7B contributed to advanced stages of tumor development and poor survival in NSCLC patients. Lentivirus-mediated shRNA silencing of METTL7B suppressed proliferation and tumorigenesis of cancer cells in vitro and in vivo. Investigation on gene expression profiles of NSCLC cells revealed that abundant cell cycle related genes were downregulated in the absence of METTL7B. Pathway enrichment analysis indicated that METTL7B participated in cell cycle regulation. Notably, CCND1, a key regulator for G1/S transition, was significantly decreased with the depletion of METTL7B, resulting in G0/G1 arrest, indicating that METTL7B is critical for cell cycle progression. Taken together, our findings implicate that METTL7B is essential for NSCLC development and progression. METTL7B might serve as a potential therapeutic target for NSCLC.

13.
Front Oncol ; 10: 571521, 2020.
Article in English | MEDLINE | ID: mdl-33680914

ABSTRACT

The clinical significance of mutation in multiple pulmonary nodules is largely limited by single gene mutation-directed analysis and lack of validation of gene expression profiles. New analytic strategy is urgently needed for comprehensive understanding of genomic data in multiple pulmonary nodules. In this study, we performed whole exome sequencing in 16 multiple lung nodules and 5 adjacent normal tissues from 4 patients with multiple pulmonary nodules and decoded the mutation information from a perspective of cellular functions and signaling pathways. Mutated genes as well as mutation patterns shared in more than two lesions were identified and characterized. We found that the number of mutations or mutated genes and the extent of protein structural changes caused by different mutations is positively correlated with the degree of malignancy. Moreover, the mutated genes in the nodules are associated with the molecular functions or signaling pathways related to cell proliferation and survival. We showed a developing pattern of quantity (the number of mutations/mutated genes) and quality (the extent of protein structural changes) in multiple pulmonary nodules. The mutation and mutated genes in multiple pulmonary nodules are associated with cell proliferation and survival related signaling pathways. This study provides a new perspective for comprehension of genomic mutational data and might shed new light on deciphering molecular evolution of early stage lung adenocarcinoma.

14.
Braz. j. med. biol. res ; 53(12): e9317, 2020. graf
Article in English | LILACS, Coleciona SUS | ID: biblio-1132508

ABSTRACT

LINC00355 has been reported aberrantly over-expressed and associated with poor prognosis in various types of cancer. However, reports regarding the effect of LINC00355 on lung squamous cell carcinoma (SCC) are rare. This study aimed to explore the function of LINC00355 in the development and progression of lung SCC and reveal the underlying mechanism. The expression and subcellular location of LINC00355 were determined by qRT-PCR and RNA-FISH, respectively. The lung SCC cell growth was analyzed by CCK-8 assay, transwell invasion, wound healing, colony formation, and flow cytometry assays. Reactive oxygen species level was evaluated by DCFH-DA probes. Bioinformatics online websites, luciferase reporter assay, RNA binding protein immunoprecipitation (RIP), and RNA pull-down assays were utilized to investigate the interaction among LINC00355, miR-466, and Ly-1 antibody reactive clone (LYAR). The results showed that LINC00355 was upregulated in lung SCC and was positively associated with poor overall survival in lung SCC patients. LINC00355 was mainly located in the cytoplasm of SCC cells. Additionally, LINC0035 functioned as a competing endogenous RNA (ceRNA) to target miR-466, and LYAR was identified as a direct target of miR-466. LINC00355 expression negatively correlated with miR-466 level, and positively correlated with LYAR level. Mechanistically, knockdown of LINC00355 inhibited cell proliferation, migration and invasion, promoted cell apoptosis in vitro, and suppressed tumor growth in vivo through targeting miR-466, and thus down-regulated LYAR expression. These findings provide a new sight for understanding the molecular mechanism of lung SCC and indicate that LINC00355 may serve as a potential biomarker for the diagnosis and treatment of lung SCC.


Subject(s)
Humans , Carcinoma, Squamous Cell/genetics , RNA, Long Noncoding/genetics , Lung Neoplasms/genetics , Nuclear Proteins , Gene Expression Regulation, Neoplastic , Clone Cells , MicroRNAs , Cell Line, Tumor , DNA-Binding Proteins , Lung
15.
Environ Pollut ; 253: 239-245, 2019 Oct.
Article in English | MEDLINE | ID: mdl-31319240

ABSTRACT

In the study, the effects of dimethyl phthalate (DMP) on the antioxidant defense capacity and immune functions of human erythrocytes were experimentally explored. DMP affected the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) and the contents of glutathione (GSH) and malondialdehyde (MDA) in erythrocytes, thus impairing the function of antioxidant defense system of erythrocytes. When DMP concentration increased from 0 to 28 µmol L-1, the SOD and GPX activities were increased firstly and then gradually decreased. When DMP concentration was below 20 µmol L-1, the relative activity of SOD was enhanced by DMP and the effect was known as hormesis. The relative activity of GPX was also increased when the concentration of DMP was below 12 µmol L-1. The CAT activity was more significantly inhibited by DMP than the activities of SOD and GPX, whereas the relative GSH content was increased by DMP. MDA levels were significantly changed after the exposure to DMP (0-24 µmol L-1). The experimental results of the activity of SOD and CAT, and the content of MDA also suggested that DMP could inhibit the immune functions of red blood cells (RBCs), which were further proved by the decrease of two indicators (RBC-C3b and RBC-IC) due to the destruction of C3b receptor with immune adherence function on erythrocyte membrane. The study provides a deep understanding of the toxicity of DMP on erythrocytes.


Subject(s)
Phthalic Acids/toxicity , Toxicity Tests , Antioxidants/pharmacology , Catalase/metabolism , Erythrocytes/drug effects , Glutathione/metabolism , Glutathione Peroxidase/metabolism , Humans , Malondialdehyde , Oxidative Stress/drug effects , Superoxide Dismutase/metabolism
16.
Adv Mater ; 30(43): e1801629, 2018 Oct.
Article in English | MEDLINE | ID: mdl-30252179

ABSTRACT

Van der Waals interactions in 2D materials have enabled the realization of nanoelectronics with high-density vertical integration. Yet, poor energy transport through such 2D-2D and 2D-3D interfaces can limit a device's performance due to overheating. One long-standing question in the field is how different encapsulating layers (e.g., contact metals or gate oxides) contribute to the thermal transport at the interface of 2D materials with their 3D substrates. Here, a novel self-heating/self-sensing electrical thermometry platform is developed based on atomically thin, metallic Ti3 C2 MXene sheets, which enables experimental investigation of the thermal transport at a Ti3 C2 /SiO2 interface, with and without an aluminum oxide (AlOx ) encapsulating layer. It is found that at room temperature, the thermal boundary conductance (TBC) increases from 10.8 to 19.5 MW m-2 K-1 upon AlOx encapsulation. Boltzmann transport modeling reveals that the TBC can be understood as a series combination of an external resistance between the MXene and the substrate, due to the coupling of low-frequency flexural acoustic (ZA) phonons to substrate modes, and an internal resistance between ZA and in-plane phonon modes. It is revealed that internal resistance is a bottle-neck to heat removal and that encapsulation speeds up the heat transfer into low-frequency ZA modes and reduces their depopulation, thus increasing the effective TBC.

17.
Adv Mater ; 30(21): e1706409, 2018 May.
Article in English | MEDLINE | ID: mdl-29633399

ABSTRACT

Structural design on the atomic level can provide novel chemistries of hybrid MAX phases and their MXenes. Herein, density functional theory is used to predict phase stability of quaternary i-MAX phases with in-plane chemical order and a general chemistry (W2/3 M21/3 )2 AC, where M2 = Sc, Y (W), and A = Al, Si, Ga, Ge, In, and Sn. Of over 18 compositions probed, only two-with a monoclinic C2/c structure-are predicted to be stable: (W2/3 Sc1/3 )2 AlC and (W2/3 Y1/3 )2 AlC and indeed found to exist. Selectively etching the Al and Sc/Y atoms from these 3D laminates results in W1.33 C-based MXene sheets with ordered metal divacancies. Using electrochemical experiments, this MXene is shown to be a new, promising catalyst for the hydrogen evolution reaction. The addition of yet one more element, W, to the stable of M elements known to form MAX phases, and the synthesis of a pure W-based MXene establishes that the etching of i-MAX phases is a fruitful path for creating new MXene chemistries that has hitherto been not possible, a fact that perforce increases the potential of tuning MXene properties for myriad applications.

SELECTION OF CITATIONS
SEARCH DETAIL
...