Lightweight and Ultrastrong Polymer Foams with Unusually Superior Flame Retardancy

Xu, Linli,Xiao, Linhong,Jia, Pan,Goossens, Karel,Liu, Peng,Li, Hui,Cheng, Chungui,Huang, Yong,Bielawski, Christopher W.,Geng, Jianxin American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.31

<P>High-performance flame-retardant materials are urgently needed to address outstanding issues that pertain to safety. Traditional flame retardants are toxic to the environment and/or lack the physical properties required for use in many contemporary applications. Here, we show that isocyanate-based polyimide (PI) foam, a flammable material, can exhibit unusually superior flame retardancy as well as, other excellent properties, such as being lightweight and displaying high mechanical strength, by incorporating red phosphorus (RP)-hybridized graphene. The covalent bonds formed between the graphene platelets and the PI matrix provide the resultant PI foam with a specific Young's modulus (83 kNm kg(-1)) that is comparable to or even higher than those displayed by state-of-the-art foams, including silica aerogels, polystyrene foams, and polyurethane foams. In addition, even a low content of the RP -hybridized graphene (2.2 wt %) results in an exceptionally higher limiting oxygen index (39.4) than those of traditional flame-retardant polymer-based materials (typically 20-30). The resultant PI foam also exhibits thermal insulation properties that are similar to that of air. Moreover, the RP -hybridized graphene is prepared using a one-step ball milling process in 100% yield, and does not require solvent or produce waste. The preparation of the flame-retardant PI foams can be scaled as the starting materials are commercially available and the techniques employed are industrially compatible.</P>

Effect of Rumen-protected Choline Addition on Milk Performance and Blood Metabolic Parameters in Transition Dairy Cows

Xu, Guozhong,Ye, Jun'An,Liu, Jianxin,Yu, Yueying Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.3

This work was conducted to study the effect of rumen-protected choline (RPC) addition on milk performance and blood metabolic parameters in transition dairy cows. In Experiment 1, fourteen Chinese Holstein dairy cows were supplemented with 0 or 20 g/d of RPC from 7 d before expected calving to 21 d post partum. Feeding of RPC tended to increase milk yield and milk protein percentage, while milk fat and lactose percentage were not changed. Plasma concentrations of glucose tended to increase as cows consumed RPC, while plasma concentrations of triglycerides, very low density lipoproteins, cholesterol and nonesterified fatty acids were not significantly different between the two groups. In Experiment 2, thirty-six Chinese Holstein dairy cows were supplemented with 0, 30, 60 or 90 g/d RPC from 15 d before expected calving to 15 d post partum. Feeding of RPC tended to increase yield of milk and 4% fat-corrected milk for all the lactating cows, and milk composition was similar among the four groups. Plasma concentrations of glucose were remained at a higher level in 30 or 60 g/d RPC-supplemented groups, and nonesterified fatty acids were decreased in the 30 g/d group. Concentrations of triglycerides tended to reduce in 30 and 90 g/d RPC-supplemented animals, and cholesterol was reduced in 0 or 30 g/d group. These results suggest that RPC addition tended to increase milk yield and improve blood metabolic parameters during transition dairy cows, and feeding 30 g/d of RPC may be the optimal.

SIRT5-related desuccinylation modification of AIFM1 protects against compression-induced intervertebral disc degeneration by regulating mitochondrial homeostasis

Mao Jianxin,Wang Di,Wang Dong,Wu Qi,Shang Qiliang,Gao Chu,Wang Huanbo,Wang Han,Du Mu,Peng Pandi,Jia Haoruo,Xu Xiaolong,Wang Jie,Yang Liu,Luo Zhuojing 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Mitochondrial dysfunction plays a major role in the development of intervertebral disc degeneration (IDD). Sirtuin 5 (SIRT5) participates in the maintenance of mitochondrial homeostasis through its desuccinylase activity. However, it is still unclear whether succinylation or SIRT5 is involved in the impairment of mitochondria and development of IDD induced by excessive mechanical stress. Our 4D label-free quantitative proteomic results showed decreased expression of the desuccinylase SIRT5 in rat nucleus pulposus (NP) tissues under mechanical loading. Overexpression of Sirt5 effectively alleviated, whereas knockdown of Sirt5 aggravated, the apoptosis and dysfunction of NP cells under mechanical stress, consistent with the more severe IDD phenotype of Sirt5 KO mice than wild-type mice that underwent lumbar spine instability (LSI) surgery. Moreover, immunoprecipitation-coupled mass spectrometry (IP-MS) results suggested that AIFM1 was a downstream target of SIRT5, which was verified by a Co-IP assay. We further demonstrated that reduced SIRT5 expression resulted in the increased succinylation of AIFM1, which in turn abolished the interaction between AIFM1 and CHCHD4 and thus led to the reduced electron transfer chain (ETC) complex subunits in NP cells. Reduced ETC complex subunits resulted in mitochondrial dysfunction and the subsequent occurrence of IDD under mechanical stress. Finally, we validated the efficacy of treatments targeting disrupted mitochondrial protein importation by upregulating SIRT5 expression or methylene blue (MB) administration in the compression-induced rat IDD model. In conclusion, our study provides new insights into the occurrence and development of IDD and offers promising therapeutic approaches for IDD.

Improving the thermoelectric properties of carbon nanotubes through introducing graphene nanosprings

Xiaoyan Xu,Huaping Xiao,Tao Ouyang,Jianxin Zhong 한국물리학회 2020 Current Applied Physics Vol.20 No.1

Carbon nanotube (CNT) is a typical one-dimensional nanomaterial containing sp2 hybridization states. In this paper, we investigate the ballistic thermoelectric performance of CNTs incorporating graphene nanosprings by using non-equilibrium Green's function. The calculations reveal that the thermoelectric figure of merit could be obviously improved by introducing graphene nanosprings, which is about ten times of that of pristine CNTs at 700 K. Such enhancement is mainly attributed to the remarkable suppression of phononic and electronic thermal conductance and improvement of Seebeck coefficient. In addition, compared to the zigzag graphene nanospring, introducing of the armchair case possesses better thermoelectric performance. The results presented in this paper indicate that embedding graphene nanospring is a viable method to optimize the thermoelectric performance of CNTs and could provide useful theoretical guidance for design and fabrication of CNTs-based thermoelectric devices

Interaction Matrix Based Analysis and Asymptotic Cooperative Control of Multi-agent Systems

Zhicheng Hou,Jianxin Xu,Gong Zhang,Weijun Wang,Changsoo Han 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.5

In this paper, we investigate a decentralized asymptotic cooperative control problem of multi-agent systems with leader-follower configuration. We firstly develop a new method using a proposed “interaction matrix” for the analysis of cooperation convergence of multi-agent systems, i.e. both consensus of the agents states and trajectory tracking of the whole group can be instantaneously concluded only by observing the minimum eigenvalue of the interaction matrix. For a multi-agent system, the external given desired trajectory can be partially obtained (through sensing or detecting) by the leaders, but higher-order derivatives such as acceleration and jerk of the desired trajectory cannot be obtained. In this case, by using some conventional control methods, the trajectory tracking performance is always not satisfactory when a trajectory varies aggressively w.r.t. time. For the sake of asymptotic tracking of an arbitrary given external trajectory of a multi-agent system, we develop a nonlinear cooperative controller based on the robust integral of signum of cooperative error (RISCE) technique, where the interaction matrix is used. The simulation results show asymptotic convergence of cooperation by using the proposed control, and better performance compared to composited nonlinear feedback based PD (CNF-PD) control.

Ultrahigh Energy Storage Capacitance and High Breakdown Strength in Biaxially Oriented Poly(vinylidene fluoride) Using a High-Electric-Induced Technique

Hongwei Lu,Jianxin Du,Cuiping Yu,Xingping Wang,Yanlin Gao,Weizhong Xu,Aiping Liu,Xiaoxiao Lu,Yingxin Chen 한국고분자학회 2020 Macromolecular Research Vol.28 No.6

The development of high dielectric materials with high energy densities is a crucial research domain in the modern microelectronics and power systems. The objective of this work was to develop the highly ordered crystal orientations and large ferroelectric crystalline β/γ-phases in the biaxially oriented poly(vinylidene fluoride) (BOPVDF). Importantly, a high discharged energy density and high dielectric constant was achieved by using a high-electric-induced technique. A suitable poling electric field was applied to the BOPVDF films in order to enhance the breakdown strength. Remarkably, the BOPVDF film poled at the electric field of 113 MV m-1 achieved an unprecedented discharged energy density of 25.4 J cm-3 at an ultra-high electric field of 550 MV m-1, which is by far the highest value ever achieved in flexible polymer-based capacitor films. Comparatively, the unpoled BOPVDF and commercial biaxially oriented polypropylene (BOPP) exhibited only a discharged energy density of 7.9 J cm-3 and 1.2 J cm-3, respectively. This systematic study provides a new design paradigm to exploit PVDF-based dielectric polymers for capacitor applications.

Extraction of microbial transglutaminase from Amycolatopsis sp. fermentation broth using aqueous two-phase system

Nan Shi,Hongwei Xu,Kaiyuan Guo,Chunyu Kang,Wei Zhang,Yingying Zhang,Liping Zhang,Jianxin Tan 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.8

Partitioning of microbial transglutaminase (MTG) from Amycolatopsis sp. in the polyethylene glycol (PEG)/salt-based ATPS was investigated for the first time. The key parameters such as the molecular weight of PEG (PEG 600-6000), the type and concentration of phase-forming salt (ammonium sulfate or phosphates), the pH of system (pH 5.0-8.5), and the concentration of neutral salt (0-6% NaCl, w/w) were determined. The partition coefficient of the enzyme was not linear with PEG molecular weight; PEG1000 gave better yield than others. The concentration of PEG1000, ammonium sulfate and NaCl, and the system pH showed effects with different extents on specific activity (SA) and yield of the enzyme. In the ATPS of 26% w/w PEG 1000 and 19% w/w ammonium sulfate in the presence of 5% w/w NaCl and at pH 6.0, MTG was partitioned into the PEG-rich phase with a maximum yield of 86.51% and SA was increased to 0.83. The results of SDS-PAGE showed the MTG produced by the test strain differed from the enzymes reported before. Thus, this study proves that ATPS can be used as a preliminary step for partial purification of MTG from Amycolatopsis sp. fermentation broth.

Exogenous Spermidine Improves Chilling Tolerance in Sweet Corn Seedlings by Regulation on Abscisic Acid, ROS and Ca2+ Pathways

Cai Shuyu,Wang Guofu,Xu Hua,Liu Jianxin,Luo Jie,Shen Yi 한국식물학회 2021 Journal of Plant Biology Vol.64 No.6

Chilling stress is a major abiotic constraint that affects sweet corn seedling establishment. Spermidine (Spd) is known to participate in the cold stress response in plants, nonetheless, the molecular mechanisms are largely unknown. The present study reported that exogenous Spd not only stimulated seedling growth but also enhanced photosynthetic attributes under chilling stress. Further analysis revealed that Spd application resulted in depressed abscisic acid (ABA) content and affected the expression of ABA-responsive genes. The augmented antioxidant enzymes activities, coupled with declined reactive oxygen species (ROS) content, were observed in response to Spd treatment under chilling stress. Moreover, Spd up-regulated the transcription levels of some Ca2+ transport-related genes. We propose that Spd contributes to cold tolerance in sweet corn seedlings via the regulation of genes involved in the ROS, ABA pathways and Ca2+ transport.

ANALYSIS OF LEARNING CONTROL SYSTEMS WITH FEEDBACK : Appocation to One Lind Manipulators

H. Hashimoto,Seongyun Kang,Jianxin XU,F. Harashima 제어로봇시스템학회 1987 제어로봇시스템학회 국내학술대회 논문집 Vol.1987 No.10

Tuning the Surface Properties of Graphene Oxide by Surface-Initiated Polymerization of Epoxides: An Efficient Method for Enhancing Gas Separation

Wu, Yu,Jia, Pan,Xu, Linli,Chen, Zhangyan,Xiao, Linhong,Sun, Jinhua,Zhang, Jun,Huang, Yong,Bielawski, Christopher W.,Geng, Jianxin American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.5

<P>Here, we describe an in situ approach for growing polyepoxides from the surfaces of graphene oxide (GO) using a surface-initiated polymerization reaction. The polymerization methodology is facile and general as a broad range of epoxides carrying various functional groups have been successfully polymerized by simply adding GO powders in the epoxide monomers. The resultant polyepoxide grafted GO are found to show enhanced dispersibility in various common solvents and to exhibit increased d-spacing between the basal planes. In particular, grafting poly(2,3-epoxy-1-propanol) (PEP) to GO results in a composite (i.e., GO-g-PEP) that is dispersible in water and miscible with polyether block amide, i.e., Pebax MH 1657. Preliminary studies have indicated the membranes prepared using Pebax/GO-g-PEP composites exhibit enhanced CO2 permeabilities and selectivities in comparison to H-2, O-2, or N-2. The excellent performance in gas separation is attributed to the layered structure of the GO-g-PEP sheets with enlarged d-spacing and the functional groups present on the PEP chains grafted to the surfaces of GO sheets.</P>