Microwave Absorption and Magnetic Properties of Cobalt Ferrites/Carbon Nanotubes Nanocomposites

B. B. Zhang,P. F. Wang,J. C. Xu,Y. B. Han,H. X. Jin,D. F. Jin,X. L. Peng,B. Hong,J. Li,J. Gong,H. L. Ge,Z. W. Zhu,X. Q. Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.5

Owing to the unique microstructure and the excellent dielectric properties, carbon nanotubes(CNTs) were decorated with CoFe2O4 nanoparticles to synthesize the CoFe2O4/CNTs nanocomposites by the solvothermal method. The phase structure, morphology, magnetic properties and microwave absorption performance of the as-prepared CoFe2O4/CNTs were characterized and discussed by X-ray diffraction (XRD), thermal gravity analysis (TGA), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). All results indicated that the diameter of CoFe2O4 nanoparticles decorating on the surface of CNTs increased with the solvothermal temperature. CoFe2O4/CNTs prepared at 180℃, 200℃ and 220℃ exhibited superparamagnetism, while the other samples presented ferromagnetism at room temperature. And with the increasing solvothermal temperature, the saturation magnetization and coercivity increased up to 72 emu/g and 2000 Oe for the sample prepared at 260℃ (S-26). And the reflection loss of CoFe2O4/CNTs nanocomposites increased with the solvothermal temperature up to -15.7 dB for S-26 with the bandwidth of 2.5 GHz.

Optimization of electrotransformation conditions for <i>Leuconostoc mesenteroides</i> subsp. <i>mesenteroides</i> ATCC8293

Jin, Q.,Eom, H.&#x2010,J.,Jung, J.Y.,Moon, J.S.,Kim, J.H.,Han, N.S. Blackwell Publishing Ltd 2012 Letters in applied microbiology Vol.55 No.4

<P><B>Abstract</B></P><P><B>Aims: </B> To establish an efficient genetic transformation protocol for <I>Leuconostoc</I> species, methods for competent‐cell preparation and electroporation conditions were optimized.</P><P><B>Methods and Results: </B> <I>Leuconostoc mesenteroides</I> subsp. <I>mesenteroides</I> ATCC8293 cells were sequentially treated with penicillin G and lysozyme, and the plasmid pLeuCM was subsequently transformed into the cells. Our results demonstrated that transformation efficiencies were significantly increased (100‐fold), and increased electric field strength also contributed to enhance transformation efficiency. Maximum transformation efficiency (1 × 10<SUP>4</SUP> or more transformants per μg DNA) was achieved when cells were grown in De Man, Rogosa, Sharpe (MRS) media containing 0·25 mol l<SUP>−1</SUP> sucrose and 0·8 μg ml<SUP>−1</SUP> penicillin G, followed by treatment with 600 U ml<SUP>−1</SUP> lysozyme and electroporation at a field strength of 10 kV cm<SUP>−1</SUP>. When this protocol was used to transform pLeuCM into <I>Leuc.?mesenteroides</I>, <I>Leuconostoc gelidum</I>, <I>Leuconostoc fallax</I> and <I>Leuconostoc argentinun</I>, successful transformations were obtained in all cases. Furthermore, this procedure was applicable to species belonging to other genera, including <I>Lactobacillus plantarum</I>, <I>Pediococcus pentosaceus</I> and <I>Weissella confusa.</I></P><P><B>Conclusions: </B> The results demonstrate that the transformation efficiency for <I>Leuconostoc</I> spp. could be increased via optimization of the entire electroporation procedures.</P><P><B>Significance and Impact of the Study: </B> These optimized conditions can be used for the extensive genetic study and the metabolic engineering of not only <I>Leuconostoc</I> spp. but also different species of lactic acid bacteria.</P>

High-Yield Synthesis of Single-Crystalline Gold Nano-octahedra

Li, Cuncheng,Shuford, Kevin&#x2005,L.,Park, Q.-Han,Cai, Weiping,Li, Yue,Lee, Eun&#x2005,Je,Cho, Sung&#x2005,Oh WILEY-VCH Verlag 2007 Angewandte Chemie Vol.46 No.18

<B>Graphic Abstract</B> <P>Pieces of eight: Single-crystalline Au nano-octahedra with well-defined shape and tunable size can be synthesized by a modified polyol process. The octahedral Au nanocrystals have sharp corners and display optical properties that are sensitive to the crystal sizes and the truncation of the tips. <img src='wiley_img/14337851-2007-46-18-ANIE200604167-content.gif' alt='wiley_img/14337851-2007-46-18-ANIE200604167-content'> </P>

Influence of Microstructure Evolution on Mechanical Properties, Wear Resistance and Corrosion Resistance of Ti(C,N)-Based Cermet Tools with Various WC Additions

L. B. Zhao,N. Lin,X. Q. Han,C. Ma,Z. Y. Wang,Y. H. He 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8

The efects of tungsten carbide addition on the microstructure, mechanical properties and corrosion resistance of Ti(C,N)-based cermets prepared by the sinter-HIP method are investigated through scanning electron microscope, X-ray difraction,electron back scattered difraction, mechanical test and electrochemical method. The results show that the appropriate WCaddition has an important infuence on promoting the formation of core-rim microstructure of cermet, increasing the wettability of ceramic phase and binder phase, and improving the mechanical properties. Ti(C,N)-based cermet with 5 wt% WCaddition has the highest hardness of 92.4 HRA and excellent wear resistance. However, excessive WC addition causes theappearance of slight white core phase containing plenty of W and Ti element in microstructure, which increases the fracturetoughness, and reduces the hardness and wear resistance of cermet. Additionally, the electrochemical result shows that theaddition of 5 wt% WC in cermet has the optimal corrosion resistance in 1 mol/L hydrochloric acid solution.

One Alpha-hydroxycholecalciferol Improves Growth Performance, Tibia Quality, and Meat Color of Broilers Fed Calcium- and Phosphorus-Deficient Diets

Han, J.C.,Wang, Y.L.,Qu, H.X.,Liang, F.,Zhang, J.L.,Shi, C.X.,Zhang, X.L.,Li, L.,Xie, Q.,Wang, C.L.,Yan, Y.Y.,Dong, X.S.,Cheng, Y.H. Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.2

An experiment was conducted to evaluate the effects of one alpha-hydroxycholecalciferol ($1{\alpha}$-OH $D_3$) on growth performance, tibia quality, and skin and meat color in broilers fed calcium (Ca)- and phosphorus (P)-deficient corn-soybean meal diets. A total of 288 male Ross broilers, at 21 days of age, were randomly assigned to three treatments with eight cages per treatment. Three levels of $1{\alpha}$-OH $D_3$ (0, 5, and 10 ${\mu}g$/kg) were added to a basal diet (0.50% Ca, 0.13% non-phytate phosphorus (NPP), and 0.35% total phosphorus (tP)) without vitamin $D_3$. As a result of this study, the addition of $1{\alpha}$-OH $D_3$ increased body weight gain (p<0.001), feed intake (p = 0.007), feed efficiency (p<0.001), tibia weight (p = 0.002), length (p<0.001), breaking-strength (p = 0.012), ash (p<0.001), Ca (p<0.001), and P content (p = 0.004). Dietary $1{\alpha}$-OH $D_3$ enhanced breast meat yellowness (p = 0.015) and the length and weight of the small intestine of the broilers. Moreover, $1{\alpha}$-OH $D_3$ decreased serum Ca concentration (p = 0.074) and breast meat redness (p = 0.010). These results indicate that the $1{\alpha}$-OH $D_3$ improves growth, tibia quality, and meat color in broilers fed Ca- and P-deficient corn-soybean meal diets.

Forsythia suspensa Extract Has the Potential to Substitute Antibiotic in Broiler Chicken

Han, X.,Piao, X.S.,Zhang, H.Y.,Li, P.F.,Yi, J.Q.,Zhang, Q.,Li, P. Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.4

Two experiments were conducted to investigate the potential for Forsythia suspensa extract (FSE) to substitute for antibiotic in broiler chicken. First, a well-diffusion assay procedure and a 2-fold dilution method were used to determine the bacteriostatic activity of FSE on Escherichia coli K88, staphylococcus aureus, and salmonella was assayed. An inhibitory effect of FSE was observed on the growth of these bacteria. This effect seems to be dose depended, which disappeared after 25.00, 12.50, 1.56 mg/ml. Second, a 42-d trial with 252 broiler chickens (d 1, $38.7{\pm}1.1$ g BW) was conducted to evaluate the effect of dietary supplementation of FSE in broiler chicken. The feeding program consisted of a starter diet from d 1 to 21 and a finisher diet from d 22 to 42. Dietary treatments included were: i) NC: negative control fed a corn-soybean meal based diet; ii) PC: positive control group fed based diet with chlortetracycline; and iii) FC: a test group fed with 100 mg FSE/kg diet. In this study growth performance did not differ among treatments during the starter period. However, dietary supplemental chlortetracycline and FSE increased (p<0.05) average daily gain (ADG), average daily feed intake (ADFI) compared with NC during the finisher and overall phase. Apparent digestibility of calcium on d 21, digestibility of energy and calcium on d 42 of FC was greater (p<0.05) than NC. Moreover, cecal Escherichia coli counts for birds from FC were lower (p<0.05) than NC. Dietary FSE supplementation also improved (p<0.05) villus height and villus height to crypt depth ratios in both duodenum and ileum and decreased (p<0.05) crypt depth in the duodenum. Duodenum villus height and villus height to crypt depth ratio in both duodenum and ileum from the FC group were also greater (p<0.05). Serum growth hormone and IGF-1 were not influenced by different treatments. Apparently, FSE has the potential to substitute for antibiotic in broiler chicken.

Deoxynivalenol exposure induces autophagy/apoptosis and epigenetic modification changes during porcine oocyte maturation

Han, J.,Wang, Q.C.,Zhu, C.C.,Liu, J.,Zhang, Y.,Cui, X.S.,Kim, N.H.,Sun, S.C. Academic Press 2016 Toxicology and applied pharmacology Vol.300 No.-

Deoxynivalenol (DON) is a widespread trichothecene mycotoxin which contaminates agricultural staples and elicits a complex spectrum of toxic effects on humans and animals. It has been shown that DON impairs oocyte maturation, reproductive function and causes abnormal fetal development in mammals; however, the mechanisms remain unclear. In the present study, we investigate the possible reasons of the toxic effects of DON on porcine oocytes. Our results showed that DON significantly inhibited porcine oocyte maturation and disrupted meiotic spindle by reducing p-MAPK protein level, which caused retardation of cell cycle progression. In addition, up-regulated LC3 protein expression and aberrant Lamp2, LC3 and mTOR mRNA levels were observed with DON exposure, together with Annexin V-FITC staining assay analysis, these results indicated that DON treatment induced autophagy/apoptosis in porcine oocytes. We also showed that DON exposure increased DNA methylation level in porcine oocytes through altering DNMT3A mRNA levels. Histone methylation levels were also changed showing with increased H3K27me3 and H3K4me2 protein levels, and mRNA levels of their relative methyltransferase genes, indicating that epigenetic modifications were affected. Taken together, our results suggested that DON exposure reduced porcine oocytes maturation capability through affecting cytoskeletal dynamics, cell cycle, autophagy/apoptosis and epigenetic modifications.

New estimation methodology of six complex aerodynamic admittance functions

Han, Y.,Chen, Z.Q.,Hua, X.G. Techno-Press 2010 Wind and Structures, An International Journal (WAS Vol.13 No.3

This paper describes a new method for the estimation of six complex aerodynamic admittance functions. The aerodynamic admittance functions relate buffeting forces to the incoming wind turbulent components, of which the estimation accuracy affects the prediction accuracy of the buffeting response of long-span bridges. There should be two aerodynamic admittance functions corresponding to the longitudinal and vertical turbulent components, respectively, for each gust buffeting force. Therefore, there are six aerodynamic admittance functions in all for the three buffeting forces. Sears function is a complex theoretical expression for the aerodynamic admittance function for a thin airfoil. Similarly, the aerodynamic admittance functions for a bridge deck should also be complex functions. This paper presents a separated frequency-by-frequency method for estimating the six complex aerodynamic admittance functions. A new experimental methodology using an active turbulence generator is developed to measure simultaneously all the six complex aerodynamic admittance functions. Wind tunnel tests of a thin plate model and a streamlined bridge section model are conducted in turbulent flow. The six complex aerodynamic admittance functions, determined by the developed methodology are compared with the Sears functions and Davenport's formula.

New estimation methodology of six complex aerodynamic admittance functions

Y. Han,Z.Q. Chen,X.G. Hua 한국풍공학회 2010 Wind and Structures, An International Journal (WAS Vol.13 No.3

This paper describes a new method for the estimation of six complex aerodynamic admittance functions. The aerodynamic admittance functions relate buffeting forces to the incoming wind turbulent components, of which the estimation accuracy affects the prediction accuracy of the buffeting response of long-span bridges. There should be two aerodynamic admittance functions corresponding to the longitudinal and vertical turbulent components, respectively, for each gust buffeting force. Therefore, there are six aerodynamic admittance functions in all for the three buffeting forces. Sears function is a complex theoretical expression for the aerodynamic admittance function for a thin airfoil. Similarly, the aerodynamic admittance functions for a bridge deck should also be complex functions. This paper presents a separated frequency-by-frequency method for estimating the six complex aerodynamic admittance functions. A new experimental methodology using an active turbulence generator is developed to measure simultaneously all the six complex aerodynamic admittance functions. Wind tunnel tests of a thin plate model and a streamlined bridge section model are conducted in turbulent flow. The six complex aerodynamic admittance functions, determined by the developed methodology are compared with the Sears functions and Davenport’s formula.

Research on simulation and experiment for surface topography machined by a novel point grinding wheel

Y. D. Gong,G. Q. Yin,X. L. Wen,M. Han,J. B. Yan,J. Cheng 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

Grains motion path will be changed in the point grinding process due to the existence of variable angle α. To verify the difference betweenpoint grinding and traditional grinding, the moving relationship and coordinate transformation between grinding wheel and workpieceare used to put the grain movement function equivalent to parabola, then point grinding cutting path is concluded. Based on grainsdistribution on the grinding wheel surface, the 3D geometry simulation topography of workpiece is obtained by extending the effectiveinterference trails along the axial direction. Furthermore, a vitrified bond CBN wheel with a coarse grinding area angle θ is proposed andthe principle of design and preparation of these novel grinding wheels are studied. The typical processing parameters are chosen to grindQT700 ladder shaft; the simulation results are verified by using the VHX-1000E microscope and the non-contact 3D surface profilometerto observe the workpiece surface topography and measure the surface roughness. The results indicated that the simulation microstructurescoincide well with the experimental measurements and the values of simulation roughness are 0.5 times of experiments. So, the geometricsimulation model provided an auxiliary and prediction method for the actual processing topography analysis. In addition, grindingwheels with different θ are used to grind ladder shafts with a series of grinding parameters. The influence trend of inclining angle α, cuttingdepth ap, axial feeding speed vf and grinding wheel speed vs on surface roughness is obtained. It is concluded that the values ofworkpiece surface roughness using novel grinding wheel are less than using the traditional grinding wheel under the condition of thesame processing parameters.