A recent trend: application of graphene in catalysis

Yuxin Yan,Woo In Shin,Hao Chen,Shar‑Mun Lee,Sivakumar Manickam,Svenja Hanson,Haitao Zhao,Edward Lester,Tao Wu,Cheng Heng Pang 한국탄소학회 2021 Carbon Letters Vol.31 No.2

Abstract Graphene, an allotrope of carbon in 2D structure, has revolutionised research, development and application in various disciplines since its successful isolation 16 years ago. The single layer of sp2-hybridised carbon atoms brings with it a string of unrivalled characteristics at a fraction of the price of its competitors, including platinum, gold and silver. More recently, there has been a growing trend in the application of graphene in catalysis, either as metal-free catalysts, composite catalysts or as catalyst supports. The unique and extraordinary properties of graphene have rendered it useful in increasing the reactivity and selectivity of some reactions. Owing to its large surface area, outstanding adsorptivity and high compatibility with various functional groups, graphene is able to provide a whole new level of possibilities and flexibilities to design and synthesise fit-for-purpose graphene-based catalysts for specific applications. This review is focussed on the progress, mechanisms and challenges of graphene application in four main reactions, i.e., oxygen reduction reaction, water splitting, water treatment and Fischer–Tropsch synthesis. This review also summarises the advantages and drawbacks of graphene over other commonly used catalysts. Given the inherent nature of graphene, coupled with its recent accelerated advancement in the synthesis and modification processes, it is anticipated that the application of graphene in catalysis will grow exponentially from its current stage of infancy.

The impacts of resveratrol on the retinal degeneration in a rat model of retinitis pigmentosa induced by alkylation: an in-vivo study

Weiming Yan,Yan Sun,Yutong Wang,Wangjiao Liang,Yuxin Xia,Weihua Yan,Meizhu Chen,Tao Chen,Dongliang Li 한국통합생물학회 2023 Animal cells and systems Vol.27 No.1

Upregulation of Sirtuin Type 1 (SIRT1), a nicotinamide adeninedinucleotide (NAD+)-dependentdeacetylase, has been proved to protect against ample ocular diseases, while its effect onretinitis pigmentosa (RP) has not been illustrated. The study was aimed to explore the impactsof resveratrol (RSV), a SIRT1 activator, on the photoreceptor degeneration in a rat model of RPinduced by N-methyl-N-nitrosourea (MNU), an alkylation. The rats were induced RP phenotypesvia the intraperitoneal injection of MNU. The electroretinogram was conducted and revealedthat RSV could not prevent the decline of retinal function in the RP rats. The optical coherencetomography (OCT) and the retinal histological examination were performed and showed thatthe reduced thickness of the outer nuclear layer (ONL) was not preserved by RSV intervention. The immunostaining technique was applied. Afther the MNU administration, the number of theapoptotic photoreceptors in the ONL throughout the retinasand the number of microglia cellspresent among the outer part throughout the retinas were not significantly reduced by RSV. Western blotting was also performed. The data showed that the level of SIRT1 protein wasdecreased after MNU administration, while RSV was not able to obviously alleviate thedownregulation. Our data together indicated that RSV was not able to rescue thephotoreceptor degeneration in the MNU-induced RP rats, which might be due to the MNUinducedconsumption of the NAD+.

Changes in plant anthocyanin levels in response to abiotic stresses: a meta-analysis

Yan Wenjie,Li Juanjuan,Lin Xinyue,Wang Lina,Yang Xiaoxiao,Xia Xiangyu,Zhang Yuxin,Yang Shaoyu,Li Hongbing,Deng Xiping,Ke Qingbo 한국식물생명공학회 2022 Plant biotechnology reports Vol.16 No.5

Anthocyanins are small molecule antioxidants that play important roles in plant response and resistance to abiotic stresses. Their levels increase when plants are exposed to abiotic stress. However, the general response patterns and magnitude of anthocyanin increase, and how they confer resistance to abiotic stresses, are difficult to evaluate because of the influence of experimental variables. In this study, changes in plant anthocyanin content under different abiotic stresses and the effect of anthocyanin overproduction on various physiological indicators were investigated through meta-analysis derived from 1039 datasets of 102 studies. Results showed that among the different stress types, heavy metals, especially copper (Cu) and mercury (Hg), induced the most significant synthesis of anthocyanins. Among the different types of drought treatments, mannitol caused anthocyanin content in plants to increase by 2.4-fold, which was more significant than that of polyethylene glycol and natural drought. Furthermore, UV stress led plant anthocyanins to increase 1.3-fold in C4 plants, which was higher than that in C3 plants. In addition, anthocyanins increased the most when the applied stresses were low and moderate, and of short duration. Moreover, plants overexpressing genes encoding MYB transcription factors increased anthocyanin content by 5.8-fold and significantly improved plant stress tolerance. Among the 21 physiological indicators, glutathione and proline levels increased the most in transgenic plants overproducing anthocyanins when exposed to abiotic stress. Taken together, this meta-analysis indicates that anthocyanins enhance stress tolerance by improving the antioxidant, metal-chelating, and osmoregulatory abilities of the plant. The results presented here can help guide future applications of anthocyanins as plant growth regulators in dryland agriculture and breeding for plant stress tolerance.

Thermosensitive Hydrogel Loaded with Primary Chondrocyte-Derived Exosomes Promotes Cartilage Repair by Regulating Macrophage Polarization in Osteoarthritis

Sang Xuehan,Zhao Xiuhong,Yan Lianqi,Jin Xing,Wang Xin,Wang Jianjian,Yin Zhenglu,Zhang Yuxin,Meng Zhaoxiang 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.3

BACKGROUND: Intra-articular injection is a classic strategy for the treatment of early osteoarthritis (OA). However, the local delivery of traditional therapeutic agents has limited benefits for alleviating OA. Exosomes, an important type of extracellular nanovesicle, show great potential for suppressing cartilage destruction in OA to replace drugs and stem cellbased administration. METHODS: In this study, we developed a thermosensitive, injectable hydrogel by in situ crosslinking of Pluronic F-127 and hyaluronic acid, which can be used as a slow-release carrier to durably retain primary chondrocyte-derived exosomes at damaged cartilage sites to effectively magnify their reparative effect. RESULTS: It was found that the hydrogel can sustainedly release exosomes, positively regulate chondrocytes on the proliferation, migration and differentiation, as well as efficiently induce polarization of M1 to M2 macrophages. Intraarticular injection of this exosomes-incorporated hydrogel significantly prevented cartilage destruction by promoting cartilage matrix formation. This strategy also displayed a regenerative immune phenotype characterized by a higher infiltration of CD163? regenerative M2 macrophages over CD86? M1 macrophages in synovial and chondral tissue, with a concomitant reduction in pro-inflammatory cytokines (TNF-a, IL-1b, and IL-6) and increase in anti-inflammatory cytokine (IL-10) in synovial fluid. CONCLUSION: Our results demonstrated that local sustained-release primary chondrocyte-derived exosomes may relieve OA by promoting the phenotypic transformation of macrophages from M1 to M2, which suggesting a great potential for the application in OA.

Catalytic pyrolysis of linear low-density polyethylene using recycled coal ash: Kinetic study and environmental evaluation

Jianchen Lai,Yang Meng,Yuxin Yan,Edward Lester,Tao Wu,Cheng Heng Pang 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.11

Catalytic pyrolysis offers a sustainable route to convert plastic wastes into fuel. We investigated the catalytic performance of coal ash (fly and bottom ash) at blending ratio of 5wt%, and 15wt% during pyrolysis of linear lowdensity polyethylene (LLDPE). The influence on activation energy and oil was characterized via thermogravimetric analyzer (TGA) and gas chromatography-mass spectrometry (GC-MS). Results have shown that 15 wt% bottom ash exhibited higher catalytic activity. The activation energy estimated by Coats-Redfern method decreased from 458.7 kJ·mol1 to 437.8 kJ·mol1, while the alicyclic hydrocarbon yield increased from 5.97% to 32.09%. This implies that CaO, which is abundant in bottom ash, could promote the conversion of LLDPE. Furthermore, a cradle-to-factory gate life cycle assessment was performed to investigate three scenarios (non-catalytic pyrolysis, 15 wt% fly ash, and 15 wt% bottom ash) of LLDPE conversion strategies via a normalization and weighting approach. It was found that LLDPE pyrolysis with 15 wt% bottom ash also showed the lowest normalized score of 2.83, implying the lowest environmental impact. This work has demonstrated that the recycling of coal ash, particularly bottom ash, as catalysts for LLDPE pyrolysis is effective.

Meta-analysis of the effect of melatonin application on abiotic stress tolerance in plants

Yang Xiaoxiao,Ren Jianhong,Li Juanjuan,Lin Xinyue,Xia Xiangyu,Yan Wenjie,Zhang Yuxin,Deng Xiping,Ke Qingbo 한국식물생명공학회 2023 Plant biotechnology reports Vol.17 No.1

Melatonin is a hormone-like substance that promotes plant growth and development and alleviates stress levels. Although the physiological roles of melatonin and the underlying mechanisms have been qualitatively reviewed in plants, we do not fully understand when and how to apply melatonin to maximize its benefits. Here, we performed a meta-analysis to quantitatively evaluate the effect of melatonin on abiotic stress tolerance in plants and to determine the number of parameters modulated by melatonin. Melatonin significantly alleviated the growth inhibition induced by drought stress compared with other abiotic stresses, including salt, cold, heat, nitrogen deficit, and heavy metal toxicity, mainly owing to higher photosynthesis efficiency and antioxidant enzyme activity. Furthermore, melatonin modulated plant growth in a concentration-dependent manner and was more effective when applied to plants under moderate drought stress at an early stage via root irrigation. In addition, the impact of melatonin was greater in monocots than in dicots. Moreover, endogenous melatonin levels could be significantly increased via transgenic strategies. Among melatonin biosynthesis-related gene members, ASMT has tended to have the most influence on melatonin content in plants. In light of the rapidly developing genome editing technology, quantitatively increasing endogenous melatonin level in plant would be quite useful for moderating climatic conditions and combating desertification. Taken together, our results provide guidelines for melatonin application in crops plants for improving productivity under ongoing climate change.