236 research outputs found

    Palladium Nanoparticles Supported on Ce-Metal–Organic Framework for Efficient CO Oxidation and Low-Temperature CO2 Capture

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    In this article, we report the lowest-temperature CO oxidation catalyst supported on metal–organic frameworks (MOFs). We have developed a facile, general, and effective approach based on microwave irradiation for the incorporation of Pd nanoparticle catalyst within Ce-MOF. The resulting Pd/Ce-MOF material is a unique catalyst that is capable of CO oxidation at modest temperatures and also of efficient uptake of the product CO2 gas at low temperatures. The observed catalytic activity of this material toward CO oxidation is significantly higher than those of other reported metal nanoparticles supported on MOFs. The high activity of the Pd/Ce-MOF catalyst is due to the presence of Ce(III) and Ce(IV) ions within the metal–organic framework support. The Pd nanoparticles supported on the Ce-MOF store oxygen in the form of a thin palladium oxide layer at the particle–support interface, in addition to the oxygen stored on the Ce(III)/Ce(IV) centers. Oxygen from these reservoirs can be released during CO oxidation at 373 K. At lower temperatures (273 K), the Pd/Ce-MOF has a significant CO2 uptake of 3.5 mmol/g

    Highly porous photoluminescent diazaborole-linked polymers: synthesis, characterization, and application to selective gas adsorption

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    The formation of boron–nitrogen (B–N) bonds has been widely explored for the synthesis of small molecules, oligomers, or linear polymers; however, its use in constructing porous organic frameworks remains very scarce. In this study, three highly porous diazaborole-linked polymers (DBLPs) have been synthesized by condensation reactions using 2,3,6,7,14,15-hexaaminotriptycene and aryl boronic acids. DBLPs are microporous and exhibit high Brunauer–Emmett–Teller surface area (730–986 m2 g−1) which enable their use in small gas storage and separation. At ambient pressure, the amorphous polymers show high CO2 (DBLP-4: 4.5 mmol g−1 at 273 K) and H2 (DBLP-3: 2.13 wt% at 77 K) uptake while their physicochemical nature leads to high CO2/N2 (35–42) and moderate CO2/CH4 (4.9–6.2) selectivity. The electronic impact of integrating diazaborole moieties into the backbone of these polymers was investigated for DBLP-4 which exhibits green emission with a broad peak ranging from 350 to 680 nm upon excitation with 340 nm in DMF without photobleaching. This study demonstrates the effectiveness of B–N formation in targeting highly porous frameworks with promising optical properties

    Covalent organic frameworks

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    The first members of covalent organic frameworks (COF) have been designed and successfully synthesized by condensation reactions of phenyl diboronic acid C6H4[B(OH)2]2 and hexahydroxytriphenylene C18H6(OH)6. The high crystallinity of the products (C3H2BO)6 (C9H12)1 (COF-1) and C9H4BO2 (COF-5) has allowed definitive resolution of their structure by powder X-ray diffraction methods which reveal expanded porous graphitic layers that are either staggered (COF-1, P63/mmc) or eclipsed (COF-5, P6/mmm). They exhibit high thermal stability (to temperatures up to 500- to 600-C), permanent porosity, and high surface areas (711 and 1590 m2/g, respectively) surpassing those of related inorganic frameworks. A similar approach has been used for the design of other extended structures

    Mangostins stimulate glucose uptake and inhibit adipocyte differentiation in 3T3-L1 adipocytes

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    Garcinia mangostana (Guttiferae) has interesting biological activities with potential medicinal application. α-mangostin and β-mangostin are the most abundant xanthones isolated from the species. The paper reported the inhibitory effect of the compounds on triglyceride formation, glucose uptake stimulation and gene expression effects on 3T3-L1 adipocytes. Evaluation of the effect of the compounds on triglyceride accumulation was examined by Oil red O staining. The result showed that all compounds inhibited lipid accumulation on 3T3-L1 adipocytes at concentration of 50 μM (P < 0.05) compared to MDI treated cells in a dose-dependent manner. Effect of the cells on uptake of 2-deoxy-D-[3H]glucose was significantly improved by increasing the concentration of the compounds. Analysis of gene expressions by quantitative real-time PCR demonstrated that the compounds inhibited the expression of early adipogenic transcription factor (PPARγ). In addition, the compounds enhanced the expression and plasma membrane translocation of GLUT4 in mature adipocytes. Analysis by using the adipolysis kit showed that α-mangostin particularly increases the free fatty acid release by stimulating the lipolysis pathway. Therefore, these results suggested that α-mangostin and β-mangostin have been found to have a beneficial action in diabetic complications (antiobesity effect) via stimulation of GLUT4 expression and inhibition of PPARγ expression

    Metal-organic and covalent organic frameworks (MOFs and COFs) as adsorbents for environmentally significant gases (H2, CO2, and CH4)

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    A series of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) possessing various functionalities, pore structures, and surface areas were evaluated for sorption and storage properties of environmentally significant gases (H_2, CO_2, and CH_4). It was concluded that the gas sorption behavior follows a general trend that materials with high surface area show enhanced gas uptake performance. For example, MOF-177 (SA = 5200 m^2/g) captures 7.2 wt% of H_2 at 77 K and 19 wt% of CH_4 at 298 K. In addition, MOF-177 exhibits exceptionally high gravimetric CO_2 uptake up to 120 wt% at 298 K. Similarly, the gas storage capacity for COFs seems to follow the same trend and it is determined by the apparent surface area. The architectural stability of both COFs and MOFs upon high pressure H_2 and CH_4 gas sorption measurements were manifested by isotherms which reach saturation without significant hysteresis

    Techno-economic feasibility study of solar photovoltaic power plant using RETScreen to achieve Indonesia energy transition.

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    Indonesia, a key player in the global energy transition, faces surging electricity demand and ambitious renewable energy goals. In response, the government introduced a new regulation about renewable energy tariffs, including tariffs for photovoltaic (PV). However, there remains a gap in the academic literature regarding PV power plant feasibility studies under these tariffs. To address this gap, this study investigates the feasibility of a utility-scale solar photovoltaic (PV) power plant in Indonesia, focusing on the newly implemented renewable energy tariffs based on Independent Power Producers (IPPs) and Indonesia's state-owned electricity company (PLN) perspectives. Five scenarios were developed based on the proposed 26 MW solar power plant on Nias Island utilizing RETScreen software. The results showed that based on the IPP perspective, the newly implemented renewable energy tariff was inadequate to make the project feasible, however, an introduction of a 10 USD/t CO2 emission incentive would make the project financially viable for IPPs. Therefore, it is recommended to introduce emission incentives as a strategic approach to attract investors and stimulate investment in Indonesia's PV power plants market, to accelerate Indonesia's energy transition. Conversely, the results also showed that the project is very profitable for PLN due to the significant cost-savings from the de-dieselization, leading to a reduction in the average generation cost for Nias

    Insulin mimicking activities of Cycloartane Triterpenoid in 3T3-L1 cells

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    Type 2 diabetes is a metabolic disorder characterized by insulin resistance, insulin action and caused by multifactorial etiology, including environmental factors, particularly diet and genetic components. Recently, most research on diabetes has focus on adipocyte which is used as a model for testing of insulin sensitivity and novel antidiabetic drugs. In this study, we investigated the effects of cycloartane triterpenoid on the adipocyte differentiation and glucose uptake in 3T3-L1 cells together with its underlying gene expression. The cells were treated for triglyceride accumulation with different concentration of the compound using Oil Red O staining assay. After 8-days, morphological changes and increase lipid accumulation were observed in these cells (p<0.05). Indeed, the intracellular lipid accumulation increased by 1.9 fold relative to MDI-treated control cells at concentration of 50 µM. Analysis of insulin-induced 2-deoxy-D-[3H] glucose uptake activities shows that cycloartane triterpenoids significantly (p<0.01) improved the glucose uptake with increasing the concentration of the compounds as compared to the basal. Further evaluation with the quantitative real time polymerase chain reaction (qRT-PCR) shows that mature 3T3-L1 cells treated with cycloart-24-en-3β-ol enhance pparγ and glut4 gene expression. As a result, it demonstrated that cycloartane triterpenoids enhance pparγ and glut4 gene expression. Taken together, these results suggest that cycloart-24-en-3β-ol derived from Garcinia malaccencis could improve insulin sensitivity through the activation of pparγ as a ligand and glut4

    Designed Synthesis of 3D Covalent Organic Frameworks

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    Three-dimensional covalent organic frameworks (3D COFs) were synthesized by targeting two nets based on triangular and tetrahedral nodes: ctn and bor. The respective 3D COFs were synthesized as crystalline solids by condensation reactions of tetrahedral tetra(4-dihydroxyborylphenyl) methane or tetra(4-dihydroxyborylphenyl)silane and by co-condensation of triangular 2,3,6,7,10,11-hexahydroxytriphenylene. Because these materials are entirely constructed from strong covalent bonds (C-C, C-O, C-B, and B-O), they have high thermal stabilities (400° to 500°C), and they also have high surface areas (3472 and 4210 square meters per gram for COF-102 and COF-103, respectively) and extremely low densities (0.17 grams per cubic centimeter)

    In-vitro evaluation of antibacterial potential of cyanoacrylate tissue adhesives for intraoral wound closure

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    Background: Cyanoacrylate tissue adhesives have been used as a substitute to silk for intraoral wound closure. Placement of sutures provides a corridor for accumulation of microorganisms into tissue which leads to infection. Cyanoacrylate-based adhesives exhibit many properties of an ideal wound closure agent, minimizing the problems generated by suturing thread. The antimicrobial properties of cyanoacrylates have been extensively assessed in other fields of medicine. However, there is a dearth in the literature on the antibacterial effect of cyanoacrylates in oral environment against oral microflora. Aim: To assess the antibacterial properties of two commonly used formulations of cyanoacrylate tissue adhesives against oral pathogens. Materials and Methods: Iso-amyl cyanoacrylate and a blend of n-butyl and 2-Octyl cyanoacrylates were applied on sterile filter paper discs and placed on culture plates. Plates for aerobic & anaerobic bacterial cultures were incubated in blood agar & Brain-Heart infusion agar respectively.Following incubation period, the bacterial inhibitory halos were measured in millimeters. In order to evaluate the bactericidal efficacy, samples were collected from the inhibitory halos and re-cultured on new bacterial culture plates. Antibacterial activity was assessed against five bacteria: A.actinomycetemcomitans, P.gingivalis, T.forsythia, L.amylovorus and S.aureus. Statistical analysis used:  The data collected was analysed using Mann Whitney u test. Results: Cyanoacrylates demonstrated potent inhibitory effects against all test organisms. The zones of inhibition against gram positive bacteria were found to be larger than gram negative bacteria. The bactericidal activity of Iso amyl cyanoacrylate was found to be more potent than n-butyl + 2 octyl cyanoacrylate. Conclusions: Due to its potent antibacterial properties, cyanoacrylate tissue adhesives can be considered as appealing alternatives to silk sutures for intraoral wound closure and help prevent postoperative

    Lung cancer in young patients: tumour characteristics and treatment in an Irish population

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    Background: Lung cancer is the leading cause of cancer death in both sexes in Ireland. Studies suggest that lung cancer in younger patients has distinct characteristics. The aim of this study is to define the characteristics of lung cancer in patients 55-year-old or younger in an Irish population. Methods: Data was collected retrospectively from local medical records and the hospital electronic database regarding all patients diagnosed with lung cancer aged 55-year-old and younger, from 2010–2016. Information regarding patient demographics, smoking status, tumour histology, molecular analysis, stage and location, diagnostic modality and initial treatment choice was collected. In all cases the diagnosis of lung cancer was confirmed at the regional lung cancer multidisciplinary team (MDT) meeting. Results: In total, 8% (n=130) of all cases of lung cancer diagnosed from 2010 to 2016 in our center occurred in patients aged 55 years old or younger; 83% (n=108) were 45 to 55-year-old, 15% (n=19) were 35 to 44-year-old and 2% (n=3) were younger than 35-year-old; 88% (n=115) of patients reported a smoking history. There was a female preponderance (58%, n=76), higher rates of NSCLC non-squamous subtype (53%, n=69) and an upper lobe predominance (42%, n=54); 53% (n=68) of patients had IV or extensive disease at presentation. Epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK) and Kirsten rat sarcoma oncogene (KRAS) mutation rates were 9% (n=4) and 3% (n=1) and 80% (n=4) respectively. Conclusions: Lung cancer in younger patients has distinct characteristics. This study suggests a female preponderance, high smoking rates and a predilection for the upper lobes. Further large-scale multicenter studies are required to verify these results and to clarify the responsible mechanisms
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