NANOSIZED HYDROXYAPATITE/COLLAGEN COMPOSITE

Feng, Feng, Q,L,Cui, Cui, F.Z,Wang, Wang, R.Z,Du, Du, C,Li, Li, H.D 한국재료학회 1995 Fabrication and Characterization of Advanced Mater Vol.1 No.2

This paper reported the synthesis of a nano-Hydroxyapatite(HAp)/collagen biocomposite and its biological performances. A thoroughly mixed slurry of type I collagen in supersaturated HAp solution was obtained. HAp was then controlled to precipitate on collagen by adjusting the solution properly. SEM, XRD and TEM analysis reveals that HAp in the composite was nanometer sized and uniformly dispersed oncollagen matrix. In vitro biocompatibility of this new biomaterial was evaluated in terms of its biodegradation and bioactivity. The mice macrophage and osteoblast were used for the study, and the behavior of the cells in contact with the composite was investigated by means of SEM. The observations showed that the composite can be degraded through extracellular resorption process mediated by macrophage, and they can also be well-contact with osteoblast cells, in vitro.

Microstructural Stability and Creep Performance of a Novel Low-Cost Single Crystal Superalloy

Z. H. Tan,X. G. Wang,Y. L. Du,Y. M. Li,Y. H. Yang,J. L. Liu,J. D. Liu,J. G. Li,Y. Z. Zhou,X. F. Sun 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The increasing pursuit of advanced aero-engines with lower ratio between the cost and performance has greatly promotedthe demanding of single crystal superalloys characterized by low cost and outstanding temperature capability. In this study,a novel low-cost single crystal superalloy was designed and the creep tests as well as micro-characterization were carried outon the experimental alloy. The results illustrated that the novel single crystal alloy exhibited an ideal microstructural stabilitywithout precipitating TCP phases, after long-term thermal exposure at the ultimate service temperature of third generationsingle crystal superalloys. Moreover, the experimental alloy with only 3 wt% Re addition demonstrated remarkable creepresistance and maintained a very low minimum creep rate at 1100 °C/137 MPa and 1120 °C/137 MPa, while the accumulationand coalescence of micro-pores had eventually led to the alloy fracture. Apart from that, the compact interfacial dislocationnetworks the 2nd γ′ phase were observed after high-temperature creep rupture, and the typical a < 010 > superdislocationswith relatively poor mobility was found at 1120 °C. At 760 °C/800 MPa, both the minimum creep velocity and entire creepstain was increased evidently, however, the ultimate creep rupture life of the alloy had still reached 200 h. The correspondingdeformation mechanism was identified as the combination of superdislocation pairs shearing and a/3 < 121 > partial dislocationcutting the γ′ phase with a SISF being generated. In general, the novel single crystal alloy characterized by remarkablemechanical properties and cost reduction possesses a great potential for future application in the advanced aircraft engines.

Effects of Partial or Total Replacement of Maize with Alternative Feed Source on Digestibility, Growth Performance, Blood Metabolites and Economics in Limousin Crossbred Cattle

Shi, F.H.,Fang, L.,Meng, Q.X.,Wu, H.,Du, J.P.,Xie, X.X.,Ren, L.P.,Zhou, Z.M.,Zhou, B. Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.10

Increasing cost and scarcity of maize has stimulated the use of alternative feed sources (AFS) in the diets of cattle. In this study, we investigated the effects of partial or total replacement of maize on nutrient digestibility, growth performance, blood metabolites, and economics in Limousin crossbred feedlot cattle. Forty-five $Limousin{\times}Luxi$ crossbred bulls were randomly assigned to the three treatment groups, orthodox diet (OD; 45.0% maize), partial replacement diet (PRD; 15% maize, 67% AFS), total replacement diet (TRD; 0% maize, 100% AFS). The growth feeding trial lasted for 98 days. Dry matter intake (DMI) and average daily gain (ADG) were recorded. The digestion trial was carried out after the end of the growth trial. Total faeces and feed samples were measured daily. Digestibilities of dry matter (DM) and organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were calculated. After the feeding trial, blood metabolites were measured in 12 animals from each group. Initial and final body weights did not differ significantly among treatment groups (p>0.05). The ADG and DMI were 1.72 and 8.66, 1.60 and 9.10, and 1.40 and 9.11 kg/d for OD, PRD, and TRD, respectively. The PRD and TRD exhibited lower ADG (p<0.01) and higher DMI (p<0.01) than OD. The DMI (%body weight) was comparable between groups (p>0.5). Feed efficiency of PRD and TRD were lower than OD (p<0.01). The DM digestibility decreased with reduced level of maize (p = 0.10), OM digestibility was higher in OD (p<0.05), and CP, NDF and ADF digestibilities were similar for all groups (p>0.05). Blood urea nitrogen (mg/dL) in PRD and TRD was higher than OD (p<0.01), while other blood parameters did not differ significantly. Feed costs ($/head/d) were 1.49, 0.98, and 0.72 for OD, PRD, and TRD, respectively (p<0.01). Feed costs per kg gain ($) were significantly lower for PRD (0.63) and TRD (0.54) than OD (0.89; p<0.01). Overall profit ($/head) and daily profit ($/head/d) did not differ significantly between treatments (p>0.05), although TRD showed the highest economic benefits overall (p<0.01). While a traditional diet maximized the growth rate, partial or total replacement of dietary maize with AFS proved economically feasible due to their lower costs and comparable nutrient digestibilities of DM, CP, NDF, and ADF. Partial replacement may prove economically competitive in the current situation of China.

A Study on the Plasma Biochemical Indices of Heat-Stressed Broilers

Lin, H.,Du, R.,Gu, X.H.,Li, F.C.,Zhang, Z.Y. Asian Australasian Association of Animal Productio 2000 Animal Bioscience Vol.13 No.9

Four experiments were conducted to evaluate the effect of temperature and humidity on biochemical indices of Arbor Acres broilers at different weeks of age. The alkaline phosphatase (AKP), acid phosphatase (ACP), lactic dehydrogenase (LD), creatine kinase (CK), plasma glucose (Glu), calcium (Ca), potassium (K), chloride (Cl), urea nitrogen (UN), uric acid (UA), plasma thyroxin (T4), triiodothyronine (T3) and insulin levels were determined in all the four experiments. In experiment 1, the plasma Glu, LD and CK levels were increased by heat exposure ($35{^{\circ}C}$ and 35, 60, or 85% RH, 2 h) and this effect was aggravated by longer exposure (24 h). No significant changes (p>0.05) were found in Ca concentration, activity of AKP and ACP. In experiment 2, temperature (10, 20, 30, $33{^{\circ}C}$) had significant effect on the levels of K, Cl, UN, UA levels and the activity of LD (p<0.01), but had no significant influence on the activity of CK (p>0.05). The UN, UK and LD levels were elevated by low temperature $(10{^{\circ}C})$ (p<0.01), Cl content was increased by high temperature ($(33{^{\circ}C})$ (p<0.01), and K level was decreased by high ($(33{^{\circ}C})$ or low $(10{^{\circ}C})$ temperature and increased by medium temperature $(30{^{\circ}C})$ (p<0.01). The humidity (35, 85% RH) only had significant effect on Cl concentration which was decreased by high humidity (p<0.01). In experiment 3, the result showed that only the LD and CK activity were significantly increased (p<0.01) by high temperature (7, 24, 28, $32{^{\circ}C}$) or high humidity (35, 85% RH). Temperature and humidity had no significant effect on K, Cl, UA, UN and Glu levels (p>0.05). In experiment 4 (24, 27, 30, $33{^{\circ}C}$; 30, 45, 60, 75, 90% RH), plasma T3 level was declined by high temperature $(33{^{\circ}C})$, and this phenomena disappeared in birds under high temperature and high humidity environment. T4 concentration in plasma was not affected by temperature (p>0.05), but was increased by high or low humidity (p<0.01). Neither temperature nor humidity had significant effect on plasma insulin concentration (p>0.05). The results of the four experiments suggested that broilers at different growth periods might have different thermal requirements and would response differently to heat exposure. The plasma biochemical indices themselves had big variation; the reaction of the indices to thermal exposure treatment differed with the age of broilers. The big variation of biochemical indices themselves might cover the response of indices to temperature and humidity treatments.

The Influence of Cryogenic Deformation on Bi2223 Superconducting Tapes

Y. Wang,W. Z. Luan,Z. Z. Duan,R. B. Feng,Q. Zhou,Y. N. Li,Y. X. Yao,F. Z. Du 대한금속학회 2005 METALS AND MATERIALS International Vol.11 No.1

Preparation and thermoelectric properties of AgPb18SbTe20−xSex (x = 1, 2, 4) materials

H. Li,K.F. Cai,Y. Du,H.F. Wang,S.Z. Shen,X.L. Li,C.W. Zhou,Y.Y. Wang 한국물리학회 2012 Current Applied Physics Vol.12 No.1

AgPb18SbTe20xSex (x ¼ 1, 2, 4) bulk materials were prepared by combining hydrothermal synthesis and melting. Thermoelectric properties were measured from room temperature up to 773K. The materials showed n-type conduction and exhibited degenerate semiconductor behavior. The power factors of the materials varied greatly with increase of Se content (x). Partial substitution of Se for Te in AgPb18SbTe20resulted in remarkable reduction of thermal conductivity in the whole temperature range and increase of power factor at lower temperatures; therefore, the dimensionless figure of merit, ZT, was enhanced below 600K. A maximum ZT value of w0.82 is obtained at 523K for the AgPb18SbTe18Se2 sample.

PHOTOCATALYTIC PROPERTIES OF TiO 2 /CNTs FILMS WITH DIFFERENT MORPHOLOGY ON STAINLESS STEEL SUBSTRATES

S. G. WANG,J. H. WANG,Z. R. DU,C. X. KONG,P. F. LI,C. X. WANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.1

CNTs – TiO 2 ¯lms with di®erent morphology were fabricated on stainless steel substrates throughchemical vapor hydrolysis deposition (CVHD) process and sol – gel process, respectively. Theirmorphology was characterized by scanning electron microscopy (SEM) and transmission electronmicroscopy (TEM). The photocatalytic properties of the ¯lms were tested in the degradation ofmethyl orange by UV light irradiation. The results revealed that TiO 2 nanoparticles could form acontinuous layer on the surface of CNTs through CVHD process. While for sol – gel process, mostTiO 2 nanoparticles were isolated and only a small amount of TiO 2 nanoparticles attached on thesurface of CNTs. And the photocatalytic property of TiO 2 /CNTs ¯lm synthesized throughCVHD process was better than that of TiO 2 /CNTs ¯lms synthesized through sol – gel process. Electrochemical impedance spectroscopy (EIS) analysis illuminated that TiO 2 /CNTs synthesizedthrough CVHD process displayed a smaller resistance than the sample which was synthesizedthrough sol – gel process and certi¯ed that the close combination between TiO 2 and CNTs couldminimize recombination of photogenerated electrons and holes, and thus promote the photo-catalytic property.