Efficient removal of methylene blue in aqueous solution by freeze-dried calcium alginate beads

Yafei Zhao,Hongsong Zhang,Guangxue Liu,Zonggao Hu,Rouwen Guan,Bing Zhang 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.11

Novel porous calcium alginate beads were prepared via crosslinking of calcium followed by freeze drying for investigating the adsorption performance for methylene blue. These beads possessed reduced shrinkage, highly porous lamellar structure and high specific surface area, and exhibited enhanced adsorption capacity and much faster adsorption rate compared to the non-porous beads obtained with conventional oven drying method. Methylene blue adsorption capacity increased with increasing of initial concentration and pH, while decreased with increasing of temperature. The adsorption process fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm. The maximum adsorption capacity was 961.5mg g−1 at 298.15 K. After eight successive adsorption-desorption cycles, the adsorption capacity had negligible decrease. Owing to the high adsorption capability, rapid adsorption rate, easy recovery and reusability, the freeze-dried beads imply a prospective, biodegradable and attractive adsorbent for removing contaminants from wastewater.

Decrease of Contact Resistance at the Interface of Carbon Nanotube/Electrode by Nanowelding

Bo Zhao,Yanfang Wang,Yafei Zhang 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.2

Reliable interconnection between carbon nanotubes (CNTs) and externalcircuit is one of the prerequisite in CNT electronics. In this work,ultrasonic nanowelding was used to bond CNTs with metal electrodes. Byexerting ultrasonic energy at the interface of CNT/electrode, a reliable jointwith negligible contact resistance was obtained between CNTs andelectrodes. The performance of welding is susceptible to the ultrasonicparameters such as ultrasonic power and clamping force, as well as themetal type. It is found that the metals with good ductility or low meltingpoint are easier to achieve effective joints. Moreover, interfacialcompounds are formed at the welded surface of metal Al and Fe, which isresulted from the interacting and chemical bonding of carbon and metalatoms. After nanowelding, the contact resistance between CNTs andelectrode is decreased dramatically, and the two-terminal resistance of thesample approximates to the intrinsic resistance of the CNT itself.

Surface formation and damage mechanisms of nano-ZrO 2 ceramics under axial ultrasonic-assisted grinding

Yanyan Yan,Yafei Zhang,Bo Zhao,Junli Liu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3

In this study, the surface formation and damage mechanism of hard-brittle materials in axial ultrasonic-assisted grinding (AUAG) were revealed using the grinding force and grinding force ratio. Theoretical analysis presented that the grinding force and grinding force ratio in AUAG are relatively small. AUAG is a machining method with a large tangential force and a small normal force, which can promote the removal of hard-brittle materials and reduce the surface and subsurface damage (SSD). Scratching and grinding tests of nano-ZrO 2ceramics were conducted to validate the theoretical analysis. The results demonstrated that the periodic tangential force under the AUAG promotes the nucleation and propagation of shallower lateral micro-cracks, thereby allowing the easier removal of hard-brittle materials. Additionally, the proportion of brittle fracture was less, and the surface roughness and maximum SSD depth were significantly small. Therefore, AUAG is a suitable ultra-precision machining technique for hard-brittle materials.

Nonlocal-integro-vibro analysis of vertically aligned monolayered nonuniform FGM nanorods

Yuan Yuan,Ke Zhao,Yafei Zhao,Keivan Kiani 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.5

Vibration of vertically aligned-monolayered-nonuniform nanorods consist of functionally graded materials with elastic supports has not been investigated yet. To fill this gap, the problem is examined using the elasticity theories of Eringen and Gurtin-Murdoch. The geometrical and mechanical properties of the surface layer and the bulk are allowed to vary arbitrarily across the length. The nonlocal-surface energy-based governing equations are established using differential-type and integro-type formulations, and solved by employing the Galerkin method by exploiting admissible modes approach and element-free Galerkin (EFG). Through various comparison studies, the effectiveness of the EFG in capturing both nonlocal-differential/integro-based frequencies is proved. A constructive parametric study is also conducted, and the roles of nanorods’ diameter, length, stiffness of both inter-rod’s elastic layer and elastic supports, power-law index of both constituent materials and geometry, nonlocal and surface effects on the dominant frequencies are revealed.

Removal of methylene blue from aqueous solutions by adsorption onto chemically activated halloysite nanotubes

Peng Luo,Bing Zhang,Yafei Zhao,Jinhua Wang,Haoqin Zhang,Jindun Liu 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.3

This study examines the adsorption behavior of methylene blue (MB) from aqueous solutions onto chemically activated halloysite nanotubes. Adsorption of MB depends greatly on the adsorbent dose, pH, initial concentration,temperature and contact time. The Langmuir and Freundlich models were applied to describe the equilibrium isotherms and the Langmuir model agrees very well with experimental data. The maximum adsorption capacities for MB ranged from 91.32 to 103.63 mg·g^(−1 )between 298 and 318 K. A comparison of kinetic models applied to the adsorption data was evaluated for pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion equation. The results showed the adsorption process was well described by the pseudo-second-order and intra-particle diffusion mode. Thermodynamic parameters suggest that the adsorption is spontaneous and endothermic. The obtained results indicated that the product had the potential to be utilized as low-cost and effective alternative for dye removal in wastewater.

EpiSIM: simulation of multiple epistasis, linkage disequilibrium patterns and haplotype blocks for genome-wide interaction analysis

Junliang Shang,Junying Zhang,Xiujuan Lei,Wenying Zhao,Yafei Dong 한국유전학회 2013 Genes & Genomics Vol.35 No.3

Epistasis is a ubiquitous phenomenon in genetics,and is considered to be one of the main factors in current efforts to detect missing heritability for complex diseases. Simulation is a critical tool in developing methodologies that can more effectively detect and study epistasis. Here we present a simulator, epiSIM (epistasis SIMulator), that can simulate some of the statistical properties of genetic data. EpiSIM is capable of expanding the range of the epistasis models that current simulators offer, including epistasis models that display marginal effects and those that display no marginal effects. One or more of these epistasis models can be embedded simultaneously into a single simulation data set, jointly determining the phenotype. In addition,epiSIM is independent of any outside data source in generating linkage disequilibrium patterns and haplotype blocks. We demonstrate the wide applicability of epiSIM by performing several data simulations, and examine its properties by comparing it with current representative simulators and by comparing the data that it generates with real data. Our experiments demonstrate that epiSIM is a valuable addition and a nice complement to the existing epistasis simulators. The software package is available online at https://sourceforge.net/projects/episimsimulator/files/.

Quantitative trait locus mapping and genomic selection of tobacco (Nicotiana tabacum L.) based on high-density genetic map

Tong Zhijun,Xiu Zhihui,Ming Yao,Fang Dunhuang,Chen Xuejun,Hu Yafei,Zhou Juhong,He Weiming,Jiao Fangchan,Zhang Chi,Zhao Shancen,Jin Han,Jian Jianbo,Xiao Bingguang 한국식물생명공학회 2021 Plant biotechnology reports Vol.15 No.6

Tobacco ( Nicotiana tabacum L.) is an economic crop and a model organism for studies of plant biology and genetics. As an allotetraploid plant generated from interspecific hybridization, tobacco has a massive genome (4.5 Gb). Recently, a genetic map with 45,081 single nucleotide polymorphism (SNP) markers was constructed using whole-genome sequencing data for a tobacco population including 274 individuals. This provides a basis for quantitative trait locus (QTL) mapping and genomic selection, which have been widely applied to other crops but have not been feasible in tobacco. Based on this high-density genetic map, we identified QTLs associated with important agronomic traits, chemical compounds in dry leaves, and hazardous substances in processed cigarettes. The LOD values for major QTLs were highest for agronomic traits, followed by chemical compounds and hazardous substances. In addition to the identification of molecular markers, we evaluated genomic selection models and found that BayesB had the highest prediction accuracy for the recombinant inbred line population. Our results offer new insights into the genetic mechanism underlying important traits, such as agronomic traits and quality-related chemical compounds in tobacco, and will be able to support the application of molecular breeding to tobacco.