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1.
Sensors (Basel) ; 24(14)2024 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-39065937

RESUMO

Robot navigation has transitioned from avoiding static obstacles to adopting socially aware navigation strategies for coexisting with humans. Consequently, socially aware navigation in dynamic, human-centric environments has gained prominence in the field of robotics. One of the methods for socially aware navigation, the reinforcement learning technique, has fostered its advancement. However, defining appropriate reward functions, particularly in congested environments, holds a significant challenge. These reward functions, crucial for guiding robot actions, necessitate intricate human-crafted design due to their complex nature and inability to be set automatically. The multitude of manually designed reward functions contains issues such as hyperparameter redundancy, imbalance, and inadequate representation of unique object characteristics. To address these challenges, we introduce a transformable Gaussian reward function (TGRF). The TGRF possesses two main features. First, it reduces the burden of tuning by utilizing a small number of hyperparameters that function independently. Second, it enables the application of various reward functions through its transformability. Consequently, it exhibits high performance and accelerated learning rates within the deep reinforcement learning (DRL) framework. We also validated the performance of TGRF through simulations and experiments.

2.
Cell Rep ; 43(6): 114334, 2024 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-38850532

RESUMO

Mechanically activating (MA) channels transduce numerous physiological functions. Tentonin 3/TMEM150C (TTN3) confers MA currents with slow inactivation kinetics in somato- and barosensory neurons. However, questions were raised about its role as a Piezo1 regulator and its potential as a channel pore. Here, we demonstrate that purified TTN3 proteins incorporated into the lipid bilayer displayed spontaneous and pressure-sensitive channel currents. These MA currents were conserved across vertebrates and differ from Piezo1 in activation threshold and pharmacological response. Deep neural network structure prediction programs coupled with mutagenetic analysis predicted a rectangular-shaped, tetrameric structure with six transmembrane helices and a pore at the inter-subunit center. The putative pore aligned with two helices of each subunit and had constriction sites whose mutations changed the MA currents. These findings suggest that TTN3 is a pore-forming subunit of a distinct slow inactivation MA channel, potentially possessing a tetrameric structure.


Assuntos
Canais Iônicos , Animais , Humanos , Camundongos , Sequência de Aminoácidos , Células HEK293 , Canais Iônicos/metabolismo , Canais Iônicos/química , Bicamadas Lipídicas/metabolismo , Mecanotransdução Celular , Proteínas de Membrana/metabolismo , Proteínas de Membrana/química , Mutação , Subunidades Proteicas/metabolismo
3.
Food Sci Biotechnol ; 33(6): 1449-1457, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38585559

RESUMO

Excessive hepatic lipid accumulation is closely linked to inflammation, insulin resistance, and metabolic syndromes. We hypothesized that a combined extract containing Schisandra chinensis (SCE) could alleviate hepatic lipid accumulation. Male Sprague-Dawley rats fed a high-sucrose diet (HSD) were randomly assigned to three groups (n = 6): normal diet (ND), HSD (60% kcal from sucrose), and HSD + SCE (HSD with 2.44% SCE). Liquid chromatography-tandem mass spectrometry revealed that SCE contains chlorogenic acid (5.514 ± 0.009 mg/g) and schisandrin (0.179 ± 0.002 mg/g) as bioactive components. SCE did not alter the body weight, fat mass, lean mass, or glucose levels. Strikingly, SCE effectively reduced the plasma triglyceride (TG) and hepatic TG levels compared to the HSD group. Adiposity reduction is due to decreased activity of hepatic de novo lipogenic enzymes. These results indicated that SCE has nutraceutical potential for the prevention and treatment of hepatic steatosis. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01464-1.

4.
Adv Mater ; 36(24): e2310015, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38450812

RESUMO

Negative-differential-resistance (NDR) devices offer a promising pathway for developing future computing technologies characterized by exceptionally low energy consumption, especially multivalued logic computing. Nevertheless, conventional approaches aimed at attaining the NDR phenomenon involve intricate junction configurations and/or external doping processes in the channel region, impeding the progress of NDR devices to the circuit and system levels. Here, an NDR device is presented that incorporates a channel without junctions. The NDR phenomenon is achieved by introducing a metal-insulator-semiconductor capacitor to a portion of the channel area. This approach establishes partial potential barrier and well that effectively restrict the movement of hole and electron carriers within specific voltage ranges. Consequently, this facilitates the implementation of both a ternary inverter and a ternary static-random-access-memory, which are essential components in the development of multivalued logic computing technology.

5.
Nat Commun ; 15(1): 2138, 2024 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-38459015

RESUMO

The advanced patterning process is the basis of integration technology to realize the development of next-generation high-speed, low-power consumption devices. Recently, area-selective atomic layer deposition (AS-ALD), which allows the direct deposition of target materials on the desired area using a deposition barrier, has emerged as an alternative patterning process. However, the AS-ALD process remains challenging to use for the improvement of patterning resolution and selectivity. In this study, we report a superlattice-based AS-ALD (SAS-ALD) process using a two-dimensional (2D) MoS2-MoSe2 lateral superlattice as a pre-defining template. We achieved a minimum half pitch size of a sub-10 nm scale for the resulting AS-ALD on the 2D superlattice template by controlling the duration time of chemical vapor deposition (CVD) precursors. SAS-ALD introduces a mechanism that enables selectivity through the adsorption and diffusion processes of ALD precursors, distinctly different from conventional AS-ALD method. This technique facilitates selective deposition even on small pattern sizes and is compatible with the use of highly reactive precursors like trimethyl aluminum. Moreover, it allows for the selective deposition of a variety of materials, including Al2O3, HfO2, Ru, Te, and Sb2Se3.

6.
Food Sci Biotechnol ; 33(1): 23-31, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38186625

RESUMO

Pork is the most consumed meat in South Korea, and pork belly is the preferred cut. However, pork production cannot meet the demand, leading to a heavy reliance on imports, particularly for pork bellies. In contrast, low-fat cuts face oversupply problems owing to low demand and export challenges. Pork belly fat content varies with breed, sex, growth rate, and fatty acid composition. Western countries favor higher fat saturation for processed products, whereas South Koreans prefer grilled or roasted bellies. Excessive consumption of high-fat pork cuts like pork belly, which is rich in saturated fatty acids, can increase the risk of severe diseases, highlighting the importance of reducing saturated fat intake and increasing the consumption of monounsaturated fatty acids and polyunsaturated fatty acids to mitigate these risks. The pork industry and public health sector should diversify production, promote leaner pork, and raise awareness about the implications of excessive pork consumption.

7.
Food Sci Biotechnol ; 33(2): 297-306, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38222909

RESUMO

As the world becomes a super-aged society, cognitive decline is public health problems that are increasing rapidly. A healthy diet has great potential for maintaining cognitive health. A diet that could delay the onset of neurodegenerative diseases has been developed: the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet, a hybrid form of the Mediterranean diet and the Dietary Approaches to Stop Hypertension (DASH) diet. In this review, the effects of the MIND diet on improving cognitive function, including memory, are summarized. In most studies, the higher the adherence to the MIND diet, the higher the cognitive function evaluation score, and the lower the incidence of dementia. This is because of the anti-inflammatory and antioxidant effects of the major nutritional components of the MIND diet: folate, carotenoids, polyphenols, and polyunsaturated fatty acids. Adherence to the MIND diet, containing various bioactive food ingredients, is related to cognitive improvement in the elderly population.

8.
Molecules ; 28(21)2023 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-37959759

RESUMO

Paper spray ionization mass spectrometry (PSI MS) has emerged as a notable method for the rapid analysis of biological samples. However, the typical cellulose-based paper tip is incompatible with protein detection due to the strong interaction between cellulose hydroxyl groups and proteins. In this study, we utilized a commercially available polyolefin-based synthetic paper, Teslin®, as an alternative PSI substrate for simple protein analysis. We have named this method "droplet PSI" MS, as the aqueous protein solution droplet retains its shape on the Teslin® paper tip. For droplet PSI, no further chemical pretreatment was necessary for the Teslin® substrate; the only required preparation was shaping the Teslin® paper into a triangular tip. In droplet PSI MS, protein ion signals were instantly detected from a protein solution droplet upon applying a spray solvent in situ along with high voltage (HV). When compared with conventional PSI MS, our method demonstrated superior sensitivity. The droplet PSI MS utilizing Teslin® also showcased flexibility in real-time observation of protein alterations induced by an acid additive. Additionally, the effects of spray solvent composition and the application method were discussed.


Assuntos
Celulose , Papel , Espectrometria de Massas/métodos , Solventes/química , Proteínas , Espectrometria de Massas por Ionização por Electrospray/métodos
9.
Nutrients ; 15(17)2023 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-37686886

RESUMO

Sarcopenic obesity, low muscle mass, and high body fat are growing health concerns in the aging population. This review highlights the need for standardized criteria and explores nutraceuticals as potential therapeutic agents. Sarcopenic obesity is associated with insulin resistance, inflammation, hormonal changes, and reduced physical activity. These factors lead to impaired muscle activity, intramuscular fat accumulation, and reduced protein synthesis, resulting in muscle catabolism and increased fat mass. Myostatin and irisin are myokines that regulate muscle synthesis and energy expenditure, respectively. Nutritional supplementation with vitamin D and calcium is recommended for increasing muscle mass and reducing body fat content. Testosterone therapy decreases fat mass and improves muscle strength. Vitamin K, specifically menaquinone-4 (MK-4), improves mitochondrial function and reduces muscle damage. Irisin is a hormone secreted during exercise that enhances oxidative metabolism, prevents insulin resistance and obesity, and improves bone quality. Low-glycemic-index diets and green cardamom are potential methods for managing sarcopenic obesity. In conclusion, along with exercise and dietary support, nutraceuticals, such as vitamin D, calcium, vitamin K, and natural agonists of irisin or testosterone, can serve as promising future therapeutic alternatives.


Assuntos
Resistência à Insulina , Sarcopenia , Humanos , Idoso , Sarcopenia/terapia , Cálcio , Fibronectinas , Suplementos Nutricionais , Obesidade/complicações , Obesidade/terapia , Vitaminas , Cálcio da Dieta , Vitamina K , Vitamina D/uso terapêutico
10.
Food Sci Biotechnol ; 32(10): 1445-1452, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37457404

RESUMO

Rottlerin is isolated from Mallotus japonicus, a plant rich in polyphenols. Rottlerin is a selective PKCδ-inhibitor and is also known as an uncoupler of oxidative phosphorylation and anti-neoplastic agent. However, its anti-obesity effect is yet to be established. Therefore, this study tested whether rottlerin inhibits adipogenesis and de novo lipogenesis via the LRP6/mTOR/SREBP1C pathway in 3T3-L1 adipocytes. Rottlerin dramatically decreased lipid accumulation assessed by Oil Red O as evidence to support the cellular phenotype (p < 0.001). Pivotal messenger RNA and protein expressions associated with de novo lipogenesis (SREBP1C, ACC1, FAS, and SCD1) and adipogenesis (PPARγ and C/EBPα) were subsequentially verified by rottlerin in a dose-dependent manner (p < 0.05). Further investigation revealed that rottlerin reduced the AKT/mTOR pathway via diminished total protein of LRP6 (p < 0.05). Collectively, these findings establish a causal link between rottlerin, LRP6, and the altered nutrient-sensing mTOR pathway, in which rottlerin regulates de novo lipogenesis and adipogenesis in white adipocytes.

11.
Proc Natl Acad Sci U S A ; 120(23): e2217332120, 2023 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-37253003

RESUMO

Although recent studies demonstrate active mitochondrial metabolism in cancers, the precise mechanisms through which mitochondrial factors contribute to cancer metastasis remain elusive. Through a customized mitochondrion RNAi screen, we identified succinyl-CoA ligase ADP-forming subunit beta (SUCLA2) as a critical anoikis resistance and metastasis driver in human cancers. Mechanistically, SUCLA2, but not the alpha subunit of its enzyme complex, relocates from mitochondria to the cytosol upon cell detachment where SUCLA2 then binds to and promotes the formation of stress granules. SUCLA2-mediated stress granules facilitate the protein translation of antioxidant enzymes including catalase, which mitigates oxidative stress and renders cancer cells resistant to anoikis. We provide clinical evidence that SUCLA2 expression correlates with catalase levels as well as metastatic potential in lung and breast cancer patients. These findings not only implicate SUCLA2 as an anticancer target, but also provide insight into a unique, noncanonical function of SUCLA2 that cancer cells co-opt to metastasize.


Assuntos
Neoplasias , Succinato-CoA Ligases , Humanos , Catalase/metabolismo , Grânulos de Estresse , Succinato-CoA Ligases/metabolismo , Oxirredução
12.
Harmful Algae ; 123: 102392, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36894213

RESUMO

Pseudo-nitzschia pungens is a widely distributed marine pennate diatom. Hybrid zones, regions in which two different genotypes may interbreed, are important areas for speciation and ecology, and have been reported across the globe for this species. However, sexual reproduction between differing clades in the natural environment is yet to be observed and is difficult to predict. Here we carried out experiments using two mono-clonal cultures of P. pungens from different genotypes to measure the frequency and timing of sexual reproduction across varying biotic (growth phases and cell activity potential) and abiotic conditions (nutrients, light, turbulence). We found the mating rates and number of zygotes gradually decreased from exponential to late stationary growth phases. The maximum zygote abundance observed was 1,390 cells mL-1 and the maximum mating rate was 7.1%, both which occurred during the exponential growth phase. Conversely, only 9 cells mL-1 and a maximum mating rate of 0.1% was observed during the late stationary phase. We also found the higher the relative potential cell activity (rPCA) in parent cells, as determined by the concentration of chlorophyll a per cell and the ratio of colony formation during parent cultivations, revealed higher mating rates. Furthermore, sexual events were reduced under nutrient enrichment conditions, and mating pairs and zygotes were not formed under aphotic (dark) or shaking culture conditions (150 rpm). In order to understand the sexual reproduction of Pseudo-nitzschia in the natural environment, our results highlight that it is most likely the combination of both biotic (growth phase, Chl. a content) and abiotic factors (nutrients, light, turbulence) that will determine the successful union of intraspecific populations of P. pungens in any given region.


Assuntos
Diatomáceas , Diatomáceas/genética , Clorofila A , Reprodução , Genótipo
13.
Protein Sci ; 32(1): e4520, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36419382

RESUMO

G protein-coupled receptors (GPCRs) are in the spotlight as drug targets due to the fact that multiple research results have verified the correlation between the activation of GPCRs and disease indications. This is because the GPCRs are present across the cell membranes, which interact with either extracellular ligands or other types of compartments and simultaneously mediate intracellular signaling. Despite the importance of the GPCRs as drug targets, they are too difficult to express in soluble forms. Currently, the difficulty of preparing functional GPCRs and the lack of efficient antibody screening methods are the most challenging steps in the discovery of antibodies targeting GPCRs. In this study, we developed a powerful platform that facilitates isolating GPCR-specific antibodies by obviating difficulties in GPCR preparation. The strategies include (i) conjugation of the P9 peptide, an envelope protein of Pseudomonas phi6, to the N-terminus of GPCRs to improve the expression level of the GPCRs in Escherichia coli, (ii) stabilization of the GPCRs in their active forms with amphiphilic poly-γ-glutamate (APG) to shield the seven hydrophobic transmembrane domains, and (iii) further limiting the size of the APG complex to improve the chance to isolate antibodies targeting the proteins-of-interest. Capitalizing on the above strategies, we could prepare GPCR proteins in their active forms as facile as other general-soluble antigen proteins. Furthermore, this protocol was validated to be successful in discovering three individual GPCR-specific antibodies targeting glucagon-like peptide-1 receptor, C-X-C chemokine receptor type 4, and prostaglandin E2 receptor 4 in this study.


Assuntos
Receptores Acoplados a Proteínas G , Transdução de Sinais , Receptores Acoplados a Proteínas G/metabolismo , Membrana Celular/metabolismo , Anticorpos/metabolismo
14.
Cell Rep ; 41(11): 111827, 2022 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-36516759

RESUMO

The cancer metastasis process involves dysregulated oncogenic kinase signaling, but how this orchestrates metabolic networks and signal cascades to promote metastasis is largely unclear. Here we report that inhibition of glutamate dehydrogenase 1 (GDH1) and ribosomal S6 kinase 2 (RSK2) synergistically attenuates cell invasion, anoikis resistance, and immune escape in lung cancer and more evidently in tumors harboring epidermal growth factor receptor (EGFR)-activating or EGFR inhibitor-resistant mutations. Mechanistically, GDH1 is activated by EGFR through phosphorylation at tyrosine 135 and, together with RSK2, enhances the cAMP response element-binding protein (CREB) activity via CaMKIV signaling, thereby promoting metastasis. Co-targeting RSK2 and GDH1 leads to enhanced intratumoral CD8 T cell infiltration. Moreover, GDH1, RSK2, and CREB phosphorylation positively correlate with EGFR mutation and activation in lung cancer patient tumors. Our findings reveal a crosstalk between kinase, metabolic, and transcription machinery in metastasis and offer an alternative combinatorial therapeutic strategy to target metastatic cancers with activated EGFRs that are often EGFR therapy resistant.


Assuntos
Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico , Neoplasias Pulmonares , Humanos , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Proteínas Quinases S6 Ribossômicas 90-kDa/genética , Proteínas Quinases S6 Ribossômicas 90-kDa/metabolismo , Receptores ErbB/metabolismo , Neoplasias Pulmonares/patologia , Fosforilação , Linhagem Celular Tumoral
15.
Cell Rep ; 39(6): 110783, 2022 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-35545042

RESUMO

The gut microbiome of humans and animals is critical to host health. Mice are used to investigate the microbiome and its influences; however, the predictive value of such studies is hindered by cage effects due to coprophagy. Our objectives were to evaluate the influence of cage density on the statistical power to detect treatment-dependent effects of a selective pressure on microbiome composition. C57BL/6 mice were separated into groups of 2 or 4 mice per cage and then assigned to groups receiving enrofloxacin, broad-spectrum antibiotics, or control. Fecal samples were collected at weeks 0, 1, and 4, along with contents of the jejunum and cecum. Bacterial DNA analysis examined microbiome richness, diversity, and variability within and between cages. Statistical analyses reveal that reduced housing density consistently results in comparable susceptibility to antibiotics, reduced cage effects, and increased statistical power to detect treatment-associated effects, justifying the practice of reduced housing density.


Assuntos
Microbioma Gastrointestinal , Animais , Antibacterianos/farmacologia , Bactérias/genética , Fezes/microbiologia , Habitação , Camundongos , Camundongos Endogâmicos C57BL
16.
Immunomedicine ; 2(2)2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36816458

RESUMO

Immune checkpoint inhibitors have improved the clinical management of some cancer cases, yet patients still fail to respond to immunotherapy. Dysregulated metabolism is a common feature of many cancers, and metabolites are known to modulate functions in cancer cells. To identify potential metabolic pathways involved in anti-tumor immune response, we employed a metabolic inhibitor-based drug screen in human lung cancer cell lines and examined expression changes in a panel of immune regulator genes. Notably, pharmacologic inhibition of dihydrofolate reductase (DHFR) downregulated cancer cell expression of cluster of differentiation 24 (CD24), an anti-phagocytic surface protein. Genetic modulation of DHFR resulted in decrease of CD24 expression, whereas tetrahydrofolate, the product of DHFR, enhanced CD24 expression. DHFR inhibition and the consequent CD24 decrease enhanced T cell-mediated tumor cell killing, whereas replenishment of DHFR or CD24 partially mitigated the immune-mediated tumor cell killing that resulted from methotrexate treatment in cancer cells. Moreover, publicly available clinical data analyses further revealed the link between DHFR, CD24, and the antitumor immune response in lung cancer patients. Our study highlights a novel connection between folate metabolism and the anti-tumor immune response and partially interprets how DHFR inhibitors lead to clinical benefits when combined with cancer immunotherapy agents.

17.
Biochem Biophys Res Commun ; 583: 162-168, 2021 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-34739856

RESUMO

Glucagon-like peptide-1 (GLP-1) is a major incretin hormone that enhances the release of insulin from pancreatic ß-cells by activating the glucagon-like peptide-1 receptor (GLP1R), which belongs to secretin-like class B of G protein-coupled receptors (GPCRs). Owing to the absence of small molecule agonist drugs to GLP1R, focus has been placed on chemical modulators that bind to the allosteric site of GLP1R. In this study, we identified novel small-molecule positive allosteric modulators of GLP1R from a chemical library consisting of commercial drug compounds using an assay system that measures the direct interaction between a purified GLP1R and its ligand, exendin-4. Two newly identified compounds, benzethonium and tamoxifen, significantly enhanced the affinity of peptide ligands for GLP1R although they lacked agonist activity by themselves. In addition, benzethonium augmented the ligand-induced accumulation of cAMP in GLP1R-transfected HEK293T cells. These compounds significantly increased the affinity of GLP1R to the alpha-subunit of G proteins, suggesting that they stabilize GLP1R in a conformation with a higher affinity to peptide ligand as well as G proteins. These compounds may lead to the design of an orally active positive allosteric modulator for GLP1R.

18.
Nat Commun ; 12(1): 4960, 2021 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-34400618

RESUMO

Agonists of glucocorticoid receptor (GR) are frequently given to cancer patients with platinum-containing chemotherapy to reduce inflammation, but how GR influences tumor growth in response to platinum-based chemotherapy such as cisplatin through inflammation-independent signaling remains largely unclear. Combined genomics and transcription factor profiling reveal that MAST1, a critical platinum resistance factor that reprograms the MAPK pathway, is upregulated upon cisplatin exposure through activated transcription factor GR. Mechanistically, cisplatin binds to C622 in GR and recruits GR to the nucleus for its activation, which induces MAST1 expression and consequently reactivates MEK signaling. GR nuclear translocation and MAST1 upregulation coordinately occur in patient tumors collected after platinum treatment, and align with patient treatment resistance. Co-treatment with dexamethasone and cisplatin restores cisplatin-resistant tumor growth, whereas addition of the MAST1 inhibitor lestaurtinib abrogates tumor growth while preserving the inhibitory effect of dexamethasone on inflammation in vivo. These findings not only provide insights into the underlying mechanism of GR in cisplatin resistance but also offer an effective alternative therapeutic strategy to improve the clinical outcome of patients receiving platinum-based chemotherapy with GR agonists.


Assuntos
Cisplatino/farmacologia , Proteínas Associadas aos Microtúbulos/metabolismo , Platina/farmacologia , Proteínas Serina-Treonina Quinases/metabolismo , Receptores de Glucocorticoides/efeitos dos fármacos , Receptores de Glucocorticoides/metabolismo , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Núcleo Celular , Sobrevivência Celular , Citocinas , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Feminino , Expressão Gênica/efeitos dos fármacos , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Associadas aos Microtúbulos/genética , Receptores de Glucocorticoides/genética , Transdução de Sinais/efeitos dos fármacos , Fatores de Transcrição , Regulação para Cima/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto
19.
ACS Appl Mater Interfaces ; 13(30): 36253-36261, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34310107

RESUMO

The arrangement of mesogenic units determines mechanical response of the liquid crystal polymer network (LCN) film to heat. Here, we show an interesting approach to programming three-dimensional patterns of the LCN films with periodic topological defects generated by applying an electric field. The mechanical properties of three representative patterned LCN films were investigated in terms of the arrangement of mesogenic units through tensile testing. Remarkably, it was determined that LCN films showed enhanced toughness and ductility as defects increased in a given area, which is related to the elastic modulus mismatch that mitigates crack propagation. Our platform can also be used to modulate the frictional force of the patterned LCN films by varying the temperature, which can provide insight into the multiplex mechanical properties of LCN films.

20.
ACS Appl Mater Interfaces ; 13(18): 21299-21309, 2021 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-33909397

RESUMO

Two-dimensional transition-metal dichalcogenides (TMDs) are of particular interest as a new active material for future triboelectric nanogenerators (TENGs) owing to their excellent electrical properties, optical transparency, flexibility, ultrathin thickness, and biocompatibility. Here, we propose a new approach to engineer the surface of TMDs via conjugation with thiolated ligands having different alkane chain lengths and to develop TMD-based TENG devices that exhibit enhanced output performance for the first time. The triboelectric charging behaviors of ligand-conjugated TMDs are successfully investigated, and the electrical output performance of TMD TENGs based on TMD-to-polymer device geometries with a vertical contact-separation mode is dramatically improved, exhibiting an output voltage of 12.2 V and a power density of 138 mW/m2. Furthermore, the ligand-conjugated TMD TENG device exhibits a highly stable operation under repeated contact and separation over 10 000 cycles, as well as high chemical stability, as a result of novel defect engineering via thiolated ligand conjugation. Detailed investigation reveals that the improved performance of the ligand-conjugated TMD TENG device originates from the synergistic effect of defect engineering and the p-type doping effect of TMDs, correlated with the increased electric potential difference between triboelectric layers. These findings provide a new potential of TMDs as a promising building block for the next-generation energy harvesting system.

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