The Chinese Journal of Process Engineering

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Effect of magnetic Fe ₃O ₄@SiO ₂ nanoparticles structure on its adsorption to DNA

Huifang XING Liangrong YANG Jiemiao YU Huizhou LIU Hao YU Wanbo LI Shuidong CUI

Chin. J. Process Eng. 2018, 18 (6): 1119-1125. DOI: 10.12034/j.issn.1009-606X.218234

Abstract （793）

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DNA purification is considered to be a critical step in biomedical applications such as genetic therapy and clinical diagnosis. These years, the magnetic silica beads are widely used in DNA purification due to the advantages of averting the use of some toxic organic solvents and being easy to auto-magnetic separation. Among them, magnetic Fe3O4@SiO2 nanoparticles (NPs) were widely used because of their stability, monodispersity, selectivity, and high separation efficiency in magnetic field. However, the shape and structure of particles may affect the DNA isolation efficiency, such as the DNA adsorption capacity and recovery rate. It has not yet been fully explored. In this work, a series of Fe3O4 NPs with different core diameters were synthesized firstly by co-precipitation and hydrothermal methods, and then further coated by silica through St?ber method. The resultant Fe3O4@SiO2 NPs were characterized by SEM, TEM, IR and BET, respectively. The DNA adsorption capacity of Fe3O4@SiO2 NPs were studied by UV?Vis, and the magnetic separation properties were also determined by magnetic response time. The results showed that in the range of 20?750 nm of particle size, the larger size particles could provide more unit planar binding sites when combining with DNA, which increased the combination stability and binding probability. Thus, the DNA binding capacity of the particles increased with the increase of particles size. In addition, the magnetic response time of Fe3O4@SiO2 NPs with different core?shell structures were also different. When the size of the core was similar, the thicker SiO2 shell around would weaken the dipole?dipole interactions between particles and reduce particles aggregation, thus the magnetic response time of NPs increased, leading to a low recovery rate within a limited operating time. Comparing the DNA adsorption capacity and recovery efficiency of particles. The Fe3O4@SiO2 NPs around 200 nm was the optimal choice for blood DNA purification, which had high recovery rate (95.2%) in a short magnetic response time (10 s).

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Frontiers of molecular dynamics simulations of protein systems-reexamine from the mesoscience perspective

Ying REN Ji XU

Chin. J. Process Eng. 2018, 18 (6): 1126-1137. DOI: 10.12034/j.issn.1009-606X.218238

Abstract （925）

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Proteins are the essential parts of living organisms and they participate in virtually every process within cells. An in-depth understanding of the spatiotemporal multi-scale structure and the dominating mechanisms of protein structures would be the basis for scientific exploration of the origin of life, the mechanisms of diseases and the development of new drugs. Due to the limitations of the spatial and temporal resolutions of current experimental methods, computer simulations, especially molecular dynamics simulations, have become one of the most important methods to study the structure and function of protein systems. This article reviewed the progress of molecular simulations and their application in the research of protein systems during the past half century, especially for molecular dynamics simulations and enhanced sampling methods. The time and space involved in protein simulations covers a wide range of scales, which makes it a great challenge to simulate the spatial-temporal multi-scale structures quickly and accurately, or to investigate the physiological process and the underlying dominating mechanisms. Therefore, this article summarized the recent development of the theoretical models and computing algorithms, and their applications in the investigations of the molecular mechanisms of the native structures and structural changes of the structured proteins, the dynamic structure ensemble of intrinsic disordered proteins and the coupled folding and binding with target protein or other biological molecules, protein complex such as molecular chaperonin, virus particle, etc. Furthermore, the evolution of the popular softwares for molecular dynamics simulations driven by the rapid development of high-performance super computers, and their acceleration of the spatial-temporal scales in molecular dynamics simulations of protein systems, were further discussed. At the end of the article, based on the rapid development of mesoscience theory and its successful applications in a variety of complex systems, the future simulation methods and theoretical research of protein systems were prospected.

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Progress on preparation of special powders using HF thermal plasma

Fangli YUAN Huacheng JIN Guolin HOU Liuyang BAI Fei DING Baoqiang LI Yunfa CHEN

Chin. J. Process Eng. 2018, 18 (6): 1138-1144. DOI: 10.12034/j.issn.1009-606X.218240

Abstract （696）

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High frequency (HF) thermal plasma with high processing temperature (up to 10000 K) in the flame zone and fast quenching rate (105?106 K/s) at the flame tail is one of the most important methods to prepare special powders. In addition, thermal plasma is a powerful tool for synthesizing well-dispersed powders in a continuous and scalable process. In this manuscript, progress on preparation of special powders using HF thermal plasma in our team was introduced. Powders with large size were fed into plasma flame and vaporized to make them vaporation, and ultrafine powders were produced after fast quenching by physical vapor deposition (PVD). Spherical nanopowders of Si, Fe, Co, Ni could be prepared by PVD. Synthesized Si nanopowders display perfect spherical shape with smooth surface and good dispersity, which exhibit super electrochemical performance as anode for Li-ion batteries. Powders with irregular shape fed into plasma flame were melted to form spherical liquid drops and fast quenched to form spherical powders. W, Mo, Nb, Cr, Ni, Ti, V spherical powders could be prepared using HF thermal plasma. Hydrogen plasma with reactive radicals could help to enhance the hydrogen reductive reaction, which could make precursors to be reduced transiently to get metal nanopowders by chemical vapor deposition (CVD). W, Ni and Cu spherical nanopowders could be prepared using CVD. Synthesized W nanopowders with well defined spherical particles exhibit high sintering activity and strengthen the mechanical properties of obtained compacts. Oxygen plasma with reactive radicals can help to tune the growth of oxides in the plasma, and oxides with various morphologies can be produced using oxygen plasma. Al2O3 spherical nanopowders can be prepared and their sintering behavior shows that the aggregates are avoided and the grains are always uniform during sintering, owing to the employment of well dispersed spheres.

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The technical state and development trend of the direct reduction of titanomagnetite by fluidized bed

Haoyan SUN Qingshan ZHU Hongzhong LI

Chin. J. Process Eng. 2018, 18 (6): 1145-1159. DOI: 10.12034/j.issn.1009-606X.218275

Abstract （844）

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Vanadium and titanium are the important production and living materials. More than 90% vanadium and titanium resources deposit in titanomagnetite. China is rich in titanomagnetite ore. But due to the limitation of blast furnace operating condition in the modern blast furnace?converter industrial process, titanium element in titanomagnetite has not been extracted and utilized. The direct reduction?electric furnace smelting process, which is the new generation environmental technology of titanomagnetite resource comprehensive extraction and utilization, has received extensive attention. By dividing the reactions in blast furnace into reduction and smelting two steps, the direct reduction?electric furnace smelting process is very beneficial to the reaction condition control. With the same smelting reactor, the process can be classified as rotary kiln, rotary hearth furnace, shaft furnace and fluidized bed direct reduction according to the different reduction reactors. Taking the advantages of high heat and mass transfer efficiency and directly using ore powder, the fluidized bed exhibits the significant advantage in the industrial application of the direct reduction of titanomagnetite. In this work, the fluidized direct reduction process of titanomagnetite was expound and compared. By analyzing the difficult reduction characteristics of titanomagnetite ore, the reduction reinforcing method by pre-oxidation was emphatically introduced. The titania?ferrous oxides in titanomagnetite ore need much higher reduction potential than normal iron oxides, resulting in the low metallization degree and the high cost. The pre-oxidation can dissociate the titania?ferrous oxides to easily reducible free Fe2O3, improving the reaction efficiency and balance metallization degree. Concluding the main influence factors of defluidization, containing operating temperature, metallization degree, particle size, reducing atmosphere, particle shape and gangue content in the fluidized direct reduction process, five restrain methods for defluidization including inert additive, carbon coating, field force addition, granulation and bed structure improvement were summarized. Further, research and development directions were proposed for MgO inert additive, carbon coated and the bed structure improving methods.

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Low rank coal pyrolysis poly-generation and hybrid power system

Wenli SONG Songgeng LI Lin DU Weigang LIN Lijie CUI Jianzhong YAO

Chin. J. Process Eng. 2018, 18 (5): 893-899. DOI: 10.12034/j.issn.1009-606X.218219

Abstract （630）

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Low rank coal account for 80% of coal resources in China. Coal pyrolysis will result in liquid tar, pyrolysis gas and solid char products. Liquid tar could be used to obtain chemicals or fuel oil, pyrolysis gas could be used as fuel or production of methane, char could be used as clean solid fuel. Continuous research and development on Chinese low rank coal pyrolysis fundamentals, process and equipment scale-up were carried out in the Institute of Process Engineering, Chinese Academy of Sciences. Laboratory scale coal fast pyrolysis experiments between 500? 850℃ showed that, the production of pyrolysis gas was increasing with the increase of temperature, while the production of liquid tar reached the maximum value at the temperature of 650℃. The ignition temperature of char increased with the increase of pyrolysis temperature. The combustion rate of char decreasd with the increase of pyrolysis temperature, but much higher than that of anthracite. A 10 t/d capacity coal pyrolysis/combustion pilot plant was build up in Langfang campus. Experimental results of Erodes sub-bituminous coal showed that, when the char was burned as fuel, the co-production of liquid tar was 6.6% and 2.5% of dried coal, pyrolysis gas was 10.3% and 18.8% of dried coal at pyrolysis temperatures 640 and 760℃ respectively. The IPE-Power, a pyrolysis bridged hybrid power system was proposed for low rank coal poly generation for coal power plant. The technical and economic analysis showed that, the IPE power system was technical and economical feasible for new power plant for coproduction of liquid tar and power. Retrofitting of 300 MW subcritical coal power plant with this technology was also discussed, the results indicate that for the retrofitted power plant the net coal consumption was decreased from 355 g/(kW?h) to 303 g/(kW?h).

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The role of microglia in Alzheimer's disease

Xiaoge LIU Lun ZHANG Xiaolin YU

Chin. J. Process Eng. 2018, 18 (5): 900-907. DOI: 10.12034/j.issn.1009-606X.218206

Abstract （792）

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Microglia, the innate immune cells of the central nervous system (CNS), serve as resident phagocytes that dynamically survey the environment and play crucial roles in CNS health and disease. Various roles are emerging for microglia in the healthy brain, from sculpting developing neuronal circuits to guiding neural plasticity. Understanding the physiological functions of microglia is important to evaluate their roles in disease. At pathological state, conditions associated with loss of cerebral homeostasis induce several dynamic microglial processes, including changes of cellular morphology, surface phenotype, secretory inflammatory mediators and proliferative responses, termed as an “activated state”. Activation and proliferation of microglia in the brain represents a prominent feature of several neurodegenerative diseases including Alzheimer's disease (AD). AD is a progressive neurodegenerative disorder that is the most common cause of dementia, which is defined as a significant, persistent, and progressive memory loss combined with cognitive impairment and personality change. The key features of AD pathology are amyloid plaques by extracellular accumulation of amyloid-β (Aβ) and intracellular neurofibrillary tangles composed of tau proteins. There is mounting evidence that microglia protect against the incidence of AD, as impaired microglial activities and altered microglial responses to Aβ are associated with increased AD risk. In CNS, microglia have protective functions by phagocytosis and clearance of toxic Aβ oligomers, which prevent the development of AD. Once activated, microglia can mediate synapse loss by engulfment of synapses via a complement-dependent mechanism, secrete inflammatory factors and exacerbate tau pathology, resulting in the neuron injury and cognitive deficits. Therefore, microglia show the double-edged sword function in AD pathogenesis. Understanding the multiple states of microglial activation and their roles in AD pathology will provide breakthrough ideas for developing AD therapeutic strategies. In this review, the role of microglia in the pathogenesis of AD and the modulation of microglia activity as a therapeutic potential will be discussed.

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Research progress on green production of sugar from sugarcane by membrane technology

Jianquan LUO Xiaofeng HANG Wei LIU Zhaoshuai WANG Xiangrong CHEN Ribo HUANG Yinhua WAN

Chin. J. Process Eng. 2018, 18 (5): 908-917. DOI: 10.12034/j.issn.1009-606X.218209

Abstract （1112）

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The green production of sugar by membrane technology is promising because the impurity removal, clarification, decolorization and concentration of sugarcane juice can be achieved by only physical separation. This technology has the advantages of not adding harmful substances, efficient, automatic and stable process, full utilization of by-products and product diversification. In this review, the research progress on green production of sugar from sugarcane by membrane technology in lab-scale experiments, pilot-scale tests and demonstration project was introduced respectively. The studies on membrane selection for sugarcane juice clarification, decolorization and concentration/purification were summarized, and the performances of ceramic and organic membranes were compared and analyzed. It was concluded that the ultrafiltration membrane with pore size from 30 nm to 100 nm was suitable for the clarification of sugarcane juice, and a loose nanofiltration membrane could achieve both high color retention and high sucrose transmission, while a tight nanofiltration was selected for the separation of sucrose and reducing sugar/salt in order to further increase the purity of juice. The recovery of residual sucrose from the membrane retentate, membrane fouling mechanisms and cleaning strategies were underlined. Diafiltration operation could recover most of sugar in the membrane concentrates, leading to a high sucrose recovery of up to 98% in the clarification and decolorization stages. Permeate flux of the ultrafiltration was dominated by membrane fouling, while for the nanofiltration, osmotic pressure played a more important role in the flux decline. Recently, the demonstration project for green production of sugar by membrane technology was successfully constructed in Guangdong Province, China, and the continuous and stable operation of such membrane filtration system was achieved, and the first batch of white sugar refined by membrane technology in China was obtained. Beside, several issues (e.g. pretreatment optimization, on-line monitor system upgradation, membrane fouling control, highly-valued product development and marketing as well as cost accounting) that need to be addressed for the industrialization of sugarcane juice refining by membrane technology were discussed.

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High-solid and multi-phases bio-reaction engineering

Lan WANG Yang LIU Hongzhang CHEN

Chin. J. Process Eng. 2018, 18 (5): 918-923. DOI: 10.12034/j.issn.1009-606X.218232

Abstract （638）

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Low solid loading bio-reaction system lead to high energy and water consumption, as well as environment pollution in fermentation industries, ing the development of high-solid bio-reaction system. High-solid bio-reaction system has the advantages of low energy consumption, less used water and environmentally-friendly. Additionally, high-solid loading leads to higher concentration of substrate and products which are benefit to reduce cost and realize the economical efficiency in production. However, many difficulties have existed in high-solid bio-reaction system apart form so many advantages. Therefore, it is of great mean to get knowledge about the characteristics and problem of high-solid bio-reaction system which will help to make the most use of its advantages. Taking enzymatic hydrolysis and fermentation of lignocellulose for an example, increasing solid loading leads to ‘solid effects’ and ‘water constraint’. Those phenomenon result in the formation of complex multi-phase system consisted by solid, liquid, gas and the microorganism. Mass transfer performance in this high-solid and multi-phases system is deficient, thus affecting lignocellulose conversion performance. Additionally, the changes of rheology characteristics in high-solid and multi-phases bio-reaction system caused by increasing solid loading make it inappropriate to apply traditional mechanical agitation which is based on shear force (i.e. shear force can results in activity loss of the enzyme and microorganism) to high-solid and multi-phases bio-reaction system, putting new requirements on agitation methods, design and amplification of bioreactor and process of high-solid and bio-reaction system. Based on several-years studies, the conception of high-solid and multi-phases bio-reaction engineering was proposed. Key factors which affect the reaction performance were analyzed from the perspective of solid matrix characteristic. Intensification method based on periodical normal force is innovated and periodic peristalsis high-solid and multi-phases bio-reaction system was developed with the expectation of providing theory and technical support for studying high-solid and multi-phases bio-reaction engineering.

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Fluidization science and technology at institute of process engineering?60th anniversary celebration for the foundation of Institute of Process Engineering

Hongzhong LI

Chin. J. Process Eng. 2018, 18 (4): 657-668. DOI: 10.12034/j.issn.1009-606X.218192

Abstract （1077）

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Institute of Process Engineering (IPE), Chinese Academy of Sciences (CAS) has undergone for 60 years since its foundation in 1958. This institute upholds the policies of Chinese Academy of Sciences, turns herself always to be in the directions of scientific frontline, great requirements of country and major fronts of national economy, and by far has acquired a series of important achievements in applied basic researches and industrial applications, especially in fluidization sciences and technologies. Under the direction of the earlier institute director Kwauk Mooson, IPE has constantly been in the internationally leading position in the area of fluidization science and technology. This paper briefly reviews a series of important achievements on fluidization theory and application at IPE. They are, for example, the generalized fluidization, idealized bubbleless fluidization, paticulatization of gas solids fluidization, relationship between structure and transfer in fluidized bed, energy-minimization multi-scale method, and micro fluidized bed characterization and definition in theory respect, and fluidized roasting of Chinese iron ores, fluidized bed pyrolysis of coal, fluidized reduction of Chinese manganese ores, low-NOx dual fluidized bed decoupling combustion of N-rich fuels, low-tar two-stage fluidization gasification, and computational simulation scale-up of MIP circulating fluidized bed reactor in dustrial application respect. This paper presents as a gift to the 60th anniversary of the IPE’s foundation, in order to impel us to inherit and to develop the truthful, pragmatic, patriotic, dedicated spirit of older scientists, and to make greater achievements in scientific research.

Content of Special collection for celebrating the 60th anniversary of IPE, CAS in our journal