08 February 2014, Volume 32 Issue 4-5

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    Spescial Issues
  • TANG Lirong, HUANG Biao, LI Tao, LU Qilin, CHEN Xuerong
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    With exquisite biological, physical and chemical properties, cellulose nanocrystals (CNCs) have been considered as an ideal drug carrier. A novel prodrug was prepared by the covalent attachment of the tosufloxacin tosylate (TFLX) onto the surface of maleated cellulose nanocrystals (MA-CNCs) with L-leucine as a spacer. The successful coupling of MA-CNCs and TFLX was detected by fourier transformation infrared spectroscopy (FTIR). The satisfactory coverage of MA- CNCs on TFLX is shown in FE- SEM micrographs. The release behaviors of TFLX- A- MA- CNCs in simulated gastric fluid (SGF), simulated intestinal fluid (SIF) and simulated colonic fluid (SCF) were investigated. The relationship between the accumulative drug release and the fluorescence response has been evaluated. The results show that the drug was efficiently entrapped by MA-CNCs carrier and presents excellent behavior for colon specificity and may be considered as a potential material for a colon-specific drug delivery system.
  • LU Yun, QIU Jian, SUN Qingfeng, LI Jian
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    To prepare a novel wood-based material, wood powder without any pre-treatment was dissolved in ionic liquid. With a circulated freezing-thawing procedure and critical point drying method, lignocellulose aerogel was successfully prepared. Morphological features and crystalline characteristics of the as-prepared material were characterized by field emission electron microscopy (SEM), transmission electron microscope, and X-ray diffraction (XRD). The results showed that the prepared lignocellulose aerogel possesses a three-dimensional structure of open fibrillar network and other novel nanostructure cellulose materials. The structure of the aerogels can be tuned from nanofibrillar to sheet-like skeletons with hierarchical micro- and nanoscale morphology by modifying the freezethaw cycles. The crystallinity first increased and then decreased along with increase of the freezing-thawing times. The formation mechanism of the lignocellulose aerogel was also discussed in this paper.
  • ZHAO Wei, LU Yun, OUYANG Huan, YAN Xiaomei, PAN Ruocai, YANG Dongjiang, SHE Xilin, LI Jian, XIA Yanzhi
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    This paper discusses the special structure and properties of algal cellulose of Ulva prolifera from green tide for preparing nanofibrillated cellulose (NFC) and aerogels with a high specific surface area. Valuable applications of NFC are reviewed for developing novel applications of Ulva prolifera. NFC was prepared using a simple grinding treatment (20000 r/min, 20 min) after the removal of polysaccharide, ester acid, protein and salt. The obtained cellulose Iα NFC had a uniform width of approximately 40 nm and a high aspect ratio. Grinding is an effective way to convert raw cellulose to nanofibrils. Furthermore, we also prepared flexible algal cellulose aerogel with a low density (23 mg/cm3) and a high specific surface area (277 cm2/g) after t-BuOH freeze-drying. It is also revealed that t-BuOH freeze-drying is an efficient way to assemble 1D NFC to meso- porous materials. All these results were confirmed by SEM, FTIR spectra, and X-ray diffraction profiles. On the basis of that, Ulva prolifera was nanofabrillated without any chemical purification by direct grinding, and algal foam was prepared with freeze-drying to fully use algae from green tide.
  • JIN Chunde, HAN Shenjie, WANG Jin, WANG Zhe
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    To obtain cheap and clean waste newspaper based cellulose aerogel (WNCA) with water and oil absorption properties, the 1-allyl-3-methylimidazolium chloride ionic liquid(AmImCl)was employed to dissolve waste newspapers without any pre-treatments. A pure cellulose hydrogel was acquired via solvent exchange from deionized water to ethanol, followed by solvent exchange from ethanol to tert-butanol, and after freeze-drying, flexible WNCA was prepared. The morphological characteristics, crystalline properties and crystallinity of the obtained WNCA were analyzed using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). The results showed that WNCA has a favorable porous structure of three-dimensional networks. The crystalline type of the WNCA is the cellulose Ⅰ type, and the crystallinity reaches 62.6%, increasing by 12.8% as compared with that of the raw material. The aerogel is able to absorb water and waste oil weighing 18-20 times of its own weight, and 99.8% of liquid can be removed through simple extrusion, indicating it has satisfactory recycling performance. Meanwhile, the WNCA shows good mechanical properties and can bounce. All reagents used in this study are environmentally friendly, providing clues for green preparation of aerogels.
  • DENG Qiaoyun, LI Dagang, SHAO Xu, HU Qinqin, LI Jing, CHEN Chuchu
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    Chitin nanofibers were prepared by chemical pretreatment and mechanical treatments. The obtained nanofiber solution formed films through vacuum filtration, and then they were impregnated into polyether sulfone (PES) resin to prepare the chitin nanofibers/PES composite films. The morphology of the nanofibers was characterized by field emission electron microscopy (FE-SEM). The light transmittance and thermal expansion properties of the chitin nanofiber/PES composite film were investigated by UV-visible spectrometer and thermomechanical analysis. The tension properties of the chitin nanofiber/PES composite film were tested by a universal materials mechanical testing machine. The results showed that the diameter of the chitin fibers reached the nanometer level, and with the combination of the mechanical processing method, the diameter of the chitin nanofibers gradually decreased. Chitin nanofiber composite films maintained high light transmittance, and compared with the resin matrix, their thermal stability and mechanical strength were apparently enhanced. Chitin nanofiber composite films possess high light transmittance and low thermal expansion, which have potential applications in optical substrates and displayers.
  • LI Qing, CHEN Wenshuai, LU Tianhong, GAO Jiali, SONG Shan, YU Haipeng, LIU Yixing
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    Cellulose molecule aggregates are an important component of the cell wall of timber. They have diameters at the nanometer scale, high aspect ratio, high specific surface area and rich surface groups. This article is based on "bottom-up" academic thought, and layer-by-layer separation of the wood powder is used to prepare microfibril. By chemical pretreatment, high-intensity ultrasound treatment and high-pressure homogenization treatment, cellulose nanofiber (CNF) was isolated from the cell walls of wood cellulose, and CNF was further assembled into aerogels by freeze-drying method. The results show that by combining high-intensity ultrasonication and high-pressure homogenization, uniform CNF with diameters within 1 and 3 nm and their bundles and stripes can be obtained. The aerogels possess a network structure formed by nanofibers or their interwoven sheets.
  • LU Qilin, TANG Lirong, YOU Huijuan, HU Yang, CHEN Yandan, CHEN Xuerong, HUANG Biao
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    Cellulose nanocrystals (CNC) were prepared by FeCl3-catalyzed hydrolysis of cellulose. The effects of temperature, reaction time, the content of FeCl3 and ultrasonic time on the yield of CNC were analyzed. The results show that at the temperature of 110℃, with reaction time of 60 min, 10% FeCl3, and ultrasonic time of 180 min, the yield of CNC reached 22%. The structural, morphological, spectroscopic and crystal properties of CNC and the charges of charged particles dispersed in the liquid phase were investigated using fourier transformation infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Zetasizer. The TEM image shows that CNC are rod-like with the diameter of 20-50 nm, the length of 200-300 nm. XRD spectra shows that CNC are celluloseⅠ with crystallinity of 76.2%. Zeta potential text shows that CNC are well dispersed in water. This catalyst system is environmentally friendly, with mild reaction conditions and simple operations. The obtained CNC have a network structure, which benefits their application in composites.
  • LU Yun, XIAO Shaoliang, GAO Runan, SUN Qingfeng, LI Jian
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    To efficiently utilize waste marine arthropod materials, α-chitin nanofibers (α-NCF) and α-chitin aerogel (NCA) were prepared from discarded crab shells via ultrasonic method combined with pre-chemical treatment. The morphological features, crystalline characteristics, chemical structures, and specific surface area of the as-prepared materials were characterized by field emission electron microscopy (FE-SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and BET method. The results showed that the diameter of the obtained chitin nanofibers was evenly about 20 nm with cross-linked thread-like structures. It was confirmed from FTIR spectra that the natural chitin/protein/mineral composites in the crab shells have been completely removed through the chemical treatment. The prepared α-NCF possess a high crystallinity of 85.4%. Meanwhile, the freezing-dried chitin aerogel has flexibility as well as a relatively high BET of 133 m2/g.
  • LI Yang, LI Dagang, XU Zhaoyang, ZHANG Ranran
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    To prepare a novel polyaniline conductive composite, nanocellulose reinforced polyaniline conductive composites were prepared using the method of in situ polymerization, where hydrochloric acid was used as the doping agent, and ammonium persulfate as the oxidant. The chemical composition, microstructure, electrical conductivity and mechanical properties of the composite were tested by fourier transform infrared spectroscopy, scanning electron microscopy, a four-probe tester and a universal mechanical testing machine. The results show that when the mass fraction of polyaniline reached 20%, the composite of nanocellulose reinforced polyaniline maintained good electrical conductivity and improved toughness.
  • LIU Zhiming, YANG Shaoli, WU Peng
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    To obtain uniform and stable cellulose aerogels, spherical cellulose aerogels were prepared by titration suspension and vacuum freeze drying method using regenerated bamboo fiber as the raw material. The results of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that spherical cellulose aerogels are typical cellulose Ⅱ structure, and the internal structure was a porous network-like one. The specific surface areas of all spherical cellulose aerogels exceed 240 m2/g. Besides, the pore sizes of spherical cellulose aerogels are below 15 nm, and the minimum density of spherical cellulose aerogels is up to 37 mg/cm3. These data indicate that spherical cellulose aerogels have high specific surface areas and small pore sizes. The results of thermal gravimetric (TG) analysis show that the maximum heat loss temperatures of large, middle and small cellulose aerogels are 364.4, 357.3 and 354.2℃, respectively, while the maximum heat loss temperature of regenerated bamboo fiber is 354.0℃. Spherical cellulose aerogels have potential applications in sewage treatment, sea oil removal and heavy metal ion adsorption.
  • LI Jun, QIU Jian, QIN Lei, XIE Xuqin
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    Wood/melamine-formaldehyde (MF) aerogel composite was obtained by vacuum impregnation and drying with supercritical fluids. The result of scanning electron microscopy shows that MF aerogel in the wood has a network structure. The result of X-ray diffraction indicates that the filling of MF aerogel in the wood would not destroy the crystallization structure of the latter. Because of chemical bonding between MF aerogel and the wood, which was proved by Fourier transform infrared spectroscopy, the resulting composite has better heat resistance. The analysis of the physical and mechanical performance of the composite shows that it has satisfactory dimensional stability and mechanical properties.
  • WAN Caichao, LU Yun, SUN Qingfeng, LI Jian
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    To obtain novel lignocellulose aerogels, the raw material, namely waste wheat straw, was purified, dissolved, replaced and dried in sequence via corresponding chemical pretreatment, dissolution and regeneration as well as freeze drying. Furthermore, a green, non-toxic and inexpensive NaOH/PEG aqueous solution was chosen to dissolve cellulose. The morphological feature, pore size distribution, crystal form, chemical construction and thermostability of the novel lignocellulose aerogel were analyzed using scanning electron microscopy (SEM), BET measurement, X- ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The results show that the obtained novel lignocellulose aerogel has a continuous and tiered threedimensional network structure. Moreover, its specific surface area reaches 99.17 m2/g, and total pore volume reaches 0.45 cm2/g. The crystal form of the novel lignocellulose aerogel is transformed from the cellulose I crystalline structure to cellulose Ⅱ crystalline structure, and the crystallinity reaches 72.3%, increasing by 23.4% as compared with that of the raw material straw. Meanwhile, the thermostability is slightly improved. Moreover, trimethylchlorosilane (TMCS) was used to hydrophobically modify the lignocellulose aerogel. In this article, a new and effective solvent for preparing lignocellulose aerogels is offered, and the novel lignocellulose aerogel having superior adsorptive properties, excellent weight capacity and high crystallinity has great application potentials as a new-style functional material.
  • Articles
  • CAO Xinrong, WANG Kun, ZHANG Jing, TANG Jintian
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    Ballistocardiogram (BCG) is a non-contact cardiac activity monitoring method. Our preliminary research of heart rate variability (HRV) was carried out using BCG. BCG signal and electrocardiography (ECG) signal of 20 subjects were measured synchronously in static, valsalva maneuver, post valsalva maneuver and post exercise states. Cardiac periods of these two signals were calculated using RR intervals of ECG and JJ intervals of BCG respectively. HRV parameters in time domain analysis, in frequency domain analysis and nonlinear analysis were calculated. The correlation of HRVBCG parameters and HRVECG parameters were checked; the significant differences between HRVBCG and HRVECG parameters were tested using paired t-test. Results showed that the variance trends of cardiac periods calculated by ECG and BCG were the same; the correlations of HRVBCG and HRVECG parameters were all above 0.81; HRVBCG parameters showed no significant differences with HRVECG during static, post valsalva maneuver and post exercise state while nPNN50, LF/HF and SD1 showed significant differences during Valsalva maneuver state.
  • GAO Wei, SHAO Wei, SU Gang, LI Jia, XIE Xiaodong
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    The aims of this study is to set up a high throughput screening model for SHP2 inhibitors and screen the potential inhibitors. By the E. coil expression system GST-SHP2 fusion protein is cloned and over expressed. High-purity SHP2 protein is purified though GSTSepharose column. After establishing the high through screening system with the colorimetric assay of SHP2, a library of 48000 pure compounds is screened using the 384 micro- plate. Among them 75 compounds have inhibitory effects over 50%. Ultimately, three inhibitors are identified as SHP2 inhibitors with high activity. The high throughput screening is a highly sensitive, inexpensive, and operationally simple assay method in identifying SHP2 inhibitors.
  • LI Nan, FENG Zhenzhong, ZHAO Yan, GU Congyou, ZHU Bo, OU Yurong
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    This paper studies the protective effect of pine pollen on renal damage in a mouse model of diabetic nephropathy and its mechanism. Fifty adult male C57BL/6J mice were used, and the mouse model of diabetic nephropathy was induced by streptozotocin (STZ). The mice were randomly divided into the control group (n=10) and the STZ model group (n=40). The latter received intraperitoneal injection of a single high dose of 150 mg body weight of STZ dissolved in citrate buffer to induce diabetic nephropathy. The control group were injected with sodium citrate buffer alone. Glucose concentrations in the tail vein blood of the mice were measured 1 week after STZ administration. Only STZ-injected mice with fasting blood glucose concentrations >11.1 mmol/L were included in the diabetic groups. After that, blood glucose and urine protein were detected in 24 hours regularly, and mice with continuing albuminuria were regarded as those with diabetic nephropathy, which totaled 28. The 28 mice were randomly divided into the STZ model group (n=14) and the pine pollen group (n=14). Mice in the pine pollen group were given pine pollen (750 mg) daily. Meanwhile, enema was performed using equal volume of normal saline in the control and STZ model groups. 7 weeks later, plasma glucose concentration, 24 h urinary protein excretion, urine creatinine, serum creatinine and plasma urea nitrogen were detected. The renal tissue was collected to assay the renal weight/body weight ratio and relative level of MDA. Masson staining and Silver staining were performed for histological analyses. The expression of p-p38 and p-ERK in renal cortical tissues was examined using Western Blot. Compared with that in the STZ model group, pine pollen apparently ameliorated renal functional lesion, reduced the renal weight/ body weight ratio and extracellular matrix accumulation. Pine pollen can also reduce the level of MDA and inhibit the activation of p38 and ERK in diabetic kidney. The results showed that pine pollen may reduce oxidative damage of the kidney and extracellular matrix accumulation by inhibiting the phosphorylation level of p38 and ERK in renal cortical tissues.
  • ZOU Guihong, LIANG Huaqing, GENG Min
    journal1. 2014, 32(4-5): 100-104. https://doi.org/10.3981/j.issn.1000-7857.2014.h1.017
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    A geoelectric numerical modeling program based on quadtree is developed using C language under VC development environment. Three experiments are used to prove the scheme based on quadtree mesh is suitable for complex geoelectric model simulations. The first experiment is the calculation of horizontal two-layer model and the result shows that the scheme using quadtree mesh does not have significantly lower numerical simulation accuracy than that using equidistant grids, but many grids are saved. The second experiment is the calculation of the model with an inclined high-resistivity plate-like body buried, with the contour and the burial depth of the body shown clearly on the dipole-dipole apparent resistivity pseudosection. The third experiment is the measuring of the model with a high-resistivity plate-like body in the vertical direction buried under 2D terrain using intermediate gradient method. After eliminating the effect of terrain factors by the comparative method, the burial depth of the high-resistivity body is calculated.
  • WEN Tingxin, ZHANG Bo
    journal1. 2014, 32(4-5): 105-109. https://doi.org/10.3981/j.issn.1000-7857.2014.h1.018
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    Slope engineering is a key project in open-pit coal mines. The stability of the slope is closely related to safety production of coal mines. Slope stability prediction is a prerequisite in slope control, faced with complexities. To quickly and effectively determine the coal mine slope stability, this paper establishes a prediction model using the random forest algorithm. Six factors influencing the slop stability were selected as input of the prediction model, including the gravity density of rocks, cohesive force, internal friction angle, slope angle, slope height and pore water pressure, and slope stability status was selected as output of the prediction model. The random forest algorithm was used to establish the nonlinear relationship between slope stability factors and stability status. The 30 sets of measured data were used as training data set to learn and train the random forest slope stability prediction model. In addition, 12 groups of data as slope stability test data were used to test the trained prediction models. In the meantime, the accuracy of the random forest prediction models was tested by comparing them with the SVM and BP neural network prediction models. The results show that the random forest prediction model based on the selected six factors has less manual control parameters, simple structure and high accuracy. The predictive results coincide with the actual state of the slope project, indicating that the prediction model is able to predict the slope stability effectively and provide guidance to coal mine slope prevention work.
  • Reviews
  • FENG Changgen, QIAO Xiaojing, LI Wangchang
    journal1. 2014, 32(4-5): 110-115. https://doi.org/10.3981/j.issn.1000-7857.2014.h1.019
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    The development of smoke bombs is discussed from the following three aspects: the structure of the smoke bomb, wide band smoke agent, and safety and environmental friendliness. Multi-level charge and skillful design of the bomb are discussed in detail, including smoke cartridges forming a smoke screen in the air, devices for preventing assembly errors, smoke torches with deceleration devices, and floatable smoke pot. The constituents of smoke agents and improvement for safety and environmental protection were introduced, such as a stabilizer consisting of aliphatic or aromatic dicarboxylic acids for reducing gaseous ammonia which weakens the structure of a smoke body when a light-metal powder is used as the metallic reduction agent in the smoke kit. Besides safety and environmental protection, skillful design of bomb structures and development of wide band adaptation techniques will be future research directions.
  • Spescial Issues
  • WU Yiqiang, QING Yan, YAO Chunhua, WU Qinglin
    Science & Technology Review. 2014, 32(4-5): 15-21. https://doi.org/10.3981/j.issn.1000-7857.2014.h1.001
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    To better understand how plant fibers mechanically defibrillate into cellulose nanofibrils, the wood pulp fiber suspension was processed by refining in combination with intense microfluidization. Cellulose nanofibril properties, including the micro-structure, crystallinity, and degree of polymerization were characterized. Several novel composite materials based on the resulting cellulose nanofibril were prepared and their potential applications were examined. The results showed that intense microfluidization further liberated microfibril bundles (aggregations) created during refining, improving the integral properties of resultant nanofibrils. Nanofibril diameters ranged from 8 to 40 nm while lengths varied over several micrometers, and they exhibited a highly tangling network. Although the original crystal structure was preserved, nanofibril crystallinity decreased to 44%, and the degree of polymerization was reduced by 32% compared to that of pulp fiber. Due to excellent mechanical properties and high light transmittance, free-standing cellulose nanofibril films are considered as promising substrates for flexible integral circuit, LED, and optical materials. Multifunctioned cellulose nanofibril aerogels are highly porous and environmentally friendly, which can be optionally tailored for use of water purification, air filtration, intelligent control and as efficient catalysts.