A Novel Bacterial Cellulose Aerogel Modified with PGMA via ARGET ATRP Method for Catalase Immobilization

Xinhua Liu,Hongliang Zheng,Yong Li,Liping Wang,Cuie Wang 한국섬유공학회 2019 Fibers and polymers Vol.20 No.3

Formation of Poly(Glycidyl Methacrylate) (PGMA) films on bacterial cellulose (BC) supports (aerogels) wasachieved via activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP). Epoxygroups on PGMA were used for covalent coupling with catalase. Immobilized catalases on BC@PGMA were characterized by Fourier transform infrared spectroscopy (FTIR) and Typical scanning electron microscopy (SEM). The immobilized catalase amount reached a high value of 116 mg/g. Furthermore, the thermal, pH and storage stabilities of the immobilized catalase were improved significantly. After 10 use cycles, the BC@PGMA-catalase still retained approximately 63.5 % of the initial activity. This work demonstrates the potential of hierarchical nanomaterials for improving enzyme performance, leveraging the benefits of both nano- and macroscale supports. These results demonstrate that the BC@PGMA-catalase has high stability and good reusability, suggesting that the BC aerogel modified with PGMA may find applications in biotechnology and as biocatalyst.

Hierarchically porous carbon derived from tobacco waste by one-step molten salt carbonization for supercapacitor

Liu Yuxuan,Cheng Xinhua,Zhang Shenghui 한국탄소학회 2022 Carbon Letters Vol.32 No.1

High-performance carbon materials were prepared via a one-step molten salt carbonization of tobacco waste used as electrode materials for supercapacitors. Carbon material prepared by carbonization for 3 h in molten CaCl2 at 850 °C exhibits hierarchically porous structure and ideal capacitive behavior. In a three-electrode configuration with 1 mol L−1 H2SO4 aqueous solution, it delivers specific capacitance of 196.5 F g−1 at 0.2 A g−1, energy density of 27.2 Wh kg−1 at 0.2 A g−1, power density of 983.5 W kg−1 at 2 A g−1, and excellent cyclic stability with 94% capacitance retention after 5000 charge–discharge cycles at 1 A g−1. Moreover, in a symmetrical two-electrode configuration with 6 mol L−1 KOH aqueous solution, it delivers specific capacitance of 111.1 F g−1 at 0.2 A g−1, energy density of 3.8 Wh kg−1 at 0.2 A g−1, and power density of 482.0 W kg−1 at 2 A g−1. The relationship between hierarchically porous structure and capacitive performance is also discussed.

Smooth Trajectory Planning for a Parallel Manipulator with Joint Friction and Jerk Constraints

Liang Liu,Chaoying Chen,Xinhua Zhao,Yangmin Li 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.4

In order to achieve better tracking accuracy effectively, a new smooth and near time-optimal trajectoryplanning approach is proposed for a parallel manipulator subject to kinematic and dynamic constraints. The completedynamic model is constructed with consideration of all joint frictions. The presented planning problem canbe solved efficiently by formulating a new limitation curve for dynamic constraints and a reduced form for jerkconstraints. The motion trajectory is planned with quartic and quintic polynomial splines in Cartesian space andseptuple polynomial splines in joint space. Experimental results show that smaller tracking error can be obtained. The developed method can be applied to any robots with analytical inverse kinematic and dynamic solutions.

High-Quality Water-Soluble Core/Shell/Shell CdSe/CdS/ZnS Quantum Dots Balanced by Ionic and Nonionic Hydrophilic Capping Ligands

Lu Liu,Hu Xu,Bing Shen,Xinhua Zhong 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.7

Pentaerythritol tetrakis 3-mercaptopropionate (PTMP) grafted poly(acryl acid) (PAA) ionic hydrophilic oligomer PAA-PTMP (PP) and dihydrolipoic acid (DHLA) grafted methoxypoly (ethylene glycol) (mPEG) nonionic hydrophilic oligomer mPEG-DHLA (PD) have been designed, synthesized and used as co-capping ligands in water-solubilization of hydrophobic quantum dots (QDs) via ligand exchange. The obtained oligomers with multi-thiol groups could bind strongly to the surface atoms of QDs. Meanwhile, the carboxyl groups (from PP) and mPEG segment (from PD) can render QDs water-soluble, and the free carboxylic groups can possibly be used for the further bioconjugation. The resulting water-soluble QDs have been characterized by ultraviolet-visible (UV-Vis), fluorescence, Fourier transform infrared (FTIR) spectroscopy as well as transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. The water-soluble QDs have relatively small hydrodynamic size (10-12 nm), and importantly, retain high fluorescence quantum yields (up to 45%) compared with that of the originally hydrophobic QDs (49%). In addition, they have tunable surface charges and show excellent colloidal stability over a relatively broad pH range (2-13), in high salt concentration, and even after thermal treatment at 100℃. These results indicate that the water-soluble QDs coated by PP and PD oligomers have potential applications in cellular imaging and biosensor.

Mineralogy Characteristics of the Soils in the Site Stockpiled by Chromite Ore Process Residue (corp) and its Decontamination by Ex-Situ Washing

Haibo Zhang,Xinhua Liu,Lei Zhang,Longhua Wu,Yongming Luo 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Design and analysis of one-degree statically indeterminate hydraulic support

Xiangpeng Hu,Xinhua Liu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.12

To enhance the bearing capacity of traditional two- and four-legged shield hydraulic support, a one-degree statically indeterminate support was designed, and a method to control the linkage of the legs and balance ram was established. Based on the plane frame system, a two-dimensional mechanical model of the statically indeterminate support was established, and the analytical expressions for the transverse distribution interval of the boundary load were derived. The effects of the friction coefficient and balance ram specifications on the boundary load and bearing area were quantitatively analyzed. The results indicated that the bearing area is divided into two regions along the transverse direction. Furthermore, this bearing area can be increased by increasing the friction coefficient, increasing the balance ram specifications, and decreasing the tip-to-face distance under the downward motion of the support. The bearing capacity of the proposed support is considerably higher than that of the traditional support.

Progress of High-k Dielectrics Applicable to SONOS-Type Nonvolatile Semiconductor Memories

Tang, Zhenjie,Liu, Zhiguo,Zhu, Xinhua The Korean Institute of Electrical and Electronic 2010 Transactions on Electrical and Electronic Material Vol.11 No.4

As a promising candidate to replace the conventional floating gate flash memories, polysilicon-oxide-nitride-oxidesilicon (SONOS)-type nonvolatile semiconductor memories have been investigated widely in the past several years. SONOS-type memories have some advantages over the conventional floating gate flash memories, such as lower operating voltage, excellent endurance and compatibility with standard complementary metal-oxide-semiconductor (CMOS) technology. However, their operating speed and date retention characteristics are still the bottlenecks to limit the applications of SONOS-type memories. Recently, various approaches have been used to make a trade-off between the operating speed and the date retention characteristics. Application of high-k dielectrics to SONOS-type memories is a predominant route. This article provides the state-of-the-art research progress of high-k dielectrics applicable to SONOS-type nonvolatile semiconductor memories. It begins with a short description of working mechanism of SONOS-type memories, and then deals with the materials' requirements of high-k dielectrics used for SONOS-type memories. In the following section, the microstructures of high-k dielectrics used as tunneling layers, charge trapping layers and blocking layers in SONOS-type memories, and their impacts on the memory behaviors are critically reviewed. The improvement of the memory characteristics by using multilayered structures, including multilayered tunneling layer or multilayered charge trapping layer are also discussed. Finally, this review is concluded with our perspectives towards the future researches on the high-k dielectrics applicable to SONOS-type nonvolatile semiconductor memories.

Expanding Application of Immobilized Candida Antarctica Lipase B: A Green Enzyme Catalyst for Knoevenagel Condensation Reaction

Cuie Wang,Ning Wang,Xinhua Liu,Peng Wan,Xinwei He,Yongjia Shang 한국섬유공학회 2018 Fibers and polymers Vol.19 No.8

We propose a green synthesis of benzopyran compound based on immobilized lipase. Firstly, by using a combined electrospun membrane and biocompatible chitosan, we show that the chitosan-functionalized electrospun PMA-co-PAA fibrous membrane can provide effective anchoring sites for immobilization of the Candida antarctica lipase B (CALB), and a maximum loading amount of CALB (152 mg/g) can be achieved. Then, the resulting membrane displays enhanced stability in catalyzing Knoevenagel condensation reaction of salicylaldehyde with active methylene compound in mixed aqueousorganic media. The catalytic activity and stability of the CALB on chitosan-modified fiber is better than its non-immobilized counterpart. Furthermore, this immobilize CALB catalyst still retained about 45 % of the initial activity after 5 cycles, which potentially had implications for the design of “green” enzyme catalyst for sustainable organic synthesis.

Progress of High-k Dielectrics Applicable to SONOS-Type Nonvolatile Semiconductor Memories

Zhenjie Tang,Zhiguo Liu,Xinhua Zhu 한국전기전자재료학회 2010 Transactions on Electrical and Electronic Material Vol.11 No.4

As a promising candidate to replace the conventional floating gate flash memories, polysilicon-oxide-nitride-oxidesilicon (SONOS)-type nonvolatile semiconductor memories have been investigated widely in the past several years. SONOS-type memories have some advantages over the conventional floating gate flash memories, such as lower operating voltage, excellent endurance and compatibility with standard complementary metal-oxide-semiconductor (CMOS) technology. However, their operating speed and date retention characteristics are still the bottlenecks to limit the applications of SONOS-type memories. Recently, various approaches have been used to make a trade-off between the operating speed and the date retention characteristics. Application of high-k dielectrics to SONOS-type memories is a predominant route. This article provides the state-of-the-art research progress of high-k dielectrics applicable to SONOS-type nonvolatile semiconductor memories. It begins with a short description of working mechanism of SONOS-type memories, and then deals with the material ’ requirements of high-k dielectrics used for SONOS-type memories. In the following section, the microstructures of high-k dielectrics used as tunneling layers, charge trapping layers and blocking layers in SONOS-type memories, and their impacts on the memory behaviors are critically reviewed. The improvement of the memory characteristics by using multilayered structures, including multilayered tunneling layer or multilayered charge trapping layer are also discussed. Finally, this review is concluded with our perspectives towards the future researches on the high-k dielectrics applicable to SONOS-type nonvolatile semiconductor memories.

Study on the removal of chromium(III) from leather waste by a two-step method

Li Wang,Jun Liu,Yang Jin,Ming Chen,JianHong Luo,Xinhua Zhu,Yuqiang Zhang 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.79 No.-

The removal of chromium(III) from leather solid waste was carried out by two steps: the leaching stepand the ion exchange step. Orthogonal method was applied to the leaching process with H2SO4 asleaching agent and the leaching rate was nearly 100%. The adsorption and desorption of Cr3+ with 732#cation exchange resins were investigated in the ion exchange process. The effects of the resin types,temperature, rotating speed, liquid-solid ratio, initial Cr3+ concentration and time were investigated andthe optimum conditions were as follows: 732#, 333 K, 120 r/min, 20 ml/g, 280 ppm and 5 h. The removalefficiency of Cr3+ from leather hydrolysate was over 95% under optimized conditions. The desorptionefficiency of Cr3+ from loaded resins was almost 99% by three times cross-flow with Na2SO4 solution. There-adsorption of Cr3+ could achieve 95% by regenerated resins. The adsorption isotherms, kinetics andthermodynamics of Cr3+ onto 732# resins were investigated. The adsorption process appeared to followLangmuir isotherm model and the pseudo-second-order kinetic model. 4H0 = 33,816.03 kJ/mol and4S0 = 141.35 J/(mol K) were calculated. The two-step method was proved to be a sustainable andeconomic method for separating chromium from leather waste.