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91.
Kyung?Min?Yoo Seok?Won?Lee Jae?Ryoun?YounEmail author Do?Heum?Yoon Young?Eun?Cho Jae-Pil?Yu Hyung?Sang?Park 《Fibers and Polymers》2003,4(2):89-96
A vertebral cage is a hollow medical device which is used in spine surgery. By implanting the cage into the spine column,
it is possible to restore disc and relieve pressure on the nerve roots. Most cages have been made of titanium alloys but they
detract the biocompatibility. Currently PEEK (polyether ether ketone) is applied to various implants because it has good properties
like heat resistance, chemical resistance, strength, and especially biocompatibility. A new shape of vertebral cage is designed
and injection molding of PEEK is considered for production. Before injection molding of the cage, it is needed to evaluate
process conditions and properties of the final product. Variables affecting the shrinkage of the cage are considered, e.g.,
injection time, packing pressure, mold temperature, and melt temperature. By using the numerical simulation program, MOLDFLOW,
several cases are studied. Data files obtained by MOLDFLOW analysis are used for stress analysis with ABAQUS, and shrinkage
and residual stress fields are predicted. With these results, optimum process conditions are determined. 相似文献
92.
Epoxidized polybutadiene (EPB) was prepared by polybutadiene (PB) withm-chloroperbenzoic acid (MCPBA) in homogeneous solution. EPB was blended with poly(3-hydroxybutyrate) (PHB) up to 30 wt% by solution-precipitation procedure. The thermal decomposition of PHB/EPB blends was studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and differential thermal analysis (DTA). The thermograms of PHB/EPB blends contained a two-step degradation process, while that of pure PHB sample exhibited only one-step degradation process. This degradation behavior of PHB/EPB blends, which have a higher thermal stability as measured by maximum decomposition temperature and residual weight, is probably due to crosslinking reactions of the epoxide groups in the EPB component with the carboxyl chain ends of PHB fragments during the degradation process, and the occurrence of such reactions can be assigned to the exothermic peaks in their DTA thermograms. 相似文献
93.
Youn?Hee?Jeon Won?Young?Jeong Jung?Woo?Park Seung?Kook?AnEmail author 《Fibers and Polymers》2003,4(4):151-155
The abrasion behavior of three kinds of warp knitted fabrics, which are normally used for upper sole of footwear, was evaluated.
We measured the changes of mechanical and structural properties of each sample as abrasion cycle increased. Each sample showed
similar trends in compression and surface properties but there were significant differences in abrasion rate among the samples.
The mechanical properties showed remarkable differences with directions. The frictional coefficient (MIU) of fabric surface
increased at the beginning of abrasion and decreased as abrasion cycles increased. The weight and thickness of the fabric
linearly decreased with abrasion cycles. The surface roughness (SMD) and the compressional resilience (RC) decreased as abrasion
cycles increased while compressional energy (WC) increased. 相似文献
94.
The self-assembly of asymmetric ABC triblock copolymers in the ordered structure is investigated using an isothermal-isobaric
molecular dynamics simulation. Unlike symmetric ABC triblock copolymers, more fascinating morphologies are observed in asymmetric
ones because of a larger difference of incompatibility between the components. Various modes of self-assembly in assymmetric
ABC triblock copolymers are also observed depending on the block composition. When the composition of block A is changed from
0.125 to 0.25 at the samef
B
=0.25, the morphological transition from the “cylinder in cylinder” to “cylinders at cylinder” structure is observed in the
simulation. In the case of ABC triblocks withf
B
=0.5, a lamellar-type structure is changed to a cylinder-type structure with increasing the length of block A. When the mid-block
length increases further tof
B
=0.625, the “spheres on cylinder” structure is observed in both the A10B50C20 and A20B50C10 triblocks. From these results, the phase diagram of ABC triblock copolymers can be constructed.
Dedicated to Professor Won-Jei Cho on the occasion of his retirement. 相似文献
95.
Nam SM Hwang IK Yi SS Yoo KY Park OK Yan B Song W Won MH Yoon YS Seong JK 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2011,73(8):1037-1042
In this study, we investigated the effects of treadmill exercise on calretinin (CR), a marker of early postmitotic neurons, immunoreactivity in the dentate gyrus (DG) of Zucker diabetic fatty (ZDF) rats, before or after diabetes onset, and Zucker lean control (ZLC) rats. For this study, 6-week-old ZLC and prediabetic ZDF rats, and 22-week-old ZLC and ZDF rats were exercised on the treadmill. Sedentary ZLC and ZDF rats of the same age were used as exercise experiment controls. The exercised prediabetic ZDF rats did not show diabetes onset, while the sedentary prediabetic ZDF rats showed significantly increased blood glucose levels. The exercised diabetic ZDF rats exhibited a decrease in their blood glucose levels compared to the sedentary diabetic ZDF rats, but the levels were still above 20 mmol/l. ZLC rats of both ages were in the normoglycemic range. CR immunoreactivity was detected throughout the DG, including the subgranular zone and the polymorphic layer. Diabetic rats exhibited a significant decrease in the number of CR-immunoreactive cells and fibers in the DG. Exercise in the prediabetic ZDF rats significantly increased the number of CR-immunoreactive cells and fibers in the subgranular zone of the DG. In the ZLC and ZDF rats of chronic diabetic phase, exercise increased CR-immunoreactive neurons in the hilar region. These results suggest that diabetes significantly reduces the number of postmitotic CR-immunoreactive neurons and the intensity of immunoreactivity and that exercise increases these CR-related parameters in a diabetic stage-dependent manner. 相似文献
96.
Kim B Shin JH Han K Seo HW Oh Y Kang I Park C Lee BH Jang JS Kim SH Chae C 《Veterinary research communications》2011,35(7):469-475
The expression of myeloperoxidase (MPO) was examined in the swine influenza virus (SIV)-infected neutrophils in the lungs of pigs experimentally infected with swine influenza virus (SIV) subtype H1N2 by immunohistochemistry. Five pigs each from the infected and non-infected group were euthanized 1, 3, 5, 7, and 10?days post-inoculation (dpi). Immunohistochemical reactivity was mainly seen in neutrophils. The score for pulmonary histopathological lesions correlated with the score for MPO immunohistochemical reactivity (r ( s )?=?0.962, P?0.01). In addition, the score for in situ hybridization of SIV nucleic acid correlated with the score for MPO immunohistochemical reactivity (r ( s )?=?0.976, P?0.01). These results suggest neutrophils are one of the primary effector cells in the early phase of SIV infection in pigs. 相似文献
97.
Thermodynamic melting occurs at a single, time-independent temperature with a constant enthalpy value. However, substantial variation in the melting parameters (T(m onset), T(m peak), and ΔH) for sucrose, glucose, and fructose has been reported in the literature. Although a number of explanations have been put forth, they do not completely account for the observed variation. Thus, this research was performed to elucidate the fundamental mechanism underlying the loss of crystalline structure in the sugars using both thermal (Part I) and chemical (Part II) analysis approaches. A strong heating rate dependency observed in the melting parameters for the sugars implies the occurrence of a kinetic process during the loss of crystalline structure. The difference in heat capacity and modulated heat flow amplitude in the stepwise quasi-isothermal modulated differential scanning calorimetry experiments for the sugars compared to indium and mannitol (thermodynamic melting comparison materials) strongly suggests thermal decomposition as the kinetic process responsible for the loss of crystalline structure, which is the critical difference between our conclusion and others. We propose the term "apparent melting" to distinguish the loss of crystalline structure due to a kinetic process, such as thermal decomposition, from thermodynamic melting. 相似文献
98.
99.
Kim Sam Soo Leem Su Gyung Ghim Han Do Kim Joon Ho Lyoo Won Seok 《Fibers and Polymers》2003,4(4):204-209
The effect of padding solution on the microwave heat dyeing of polyester fabric was studied extensively. Polyester fabrics
were impregnated in aqueous urea solution and aqueous sodium chloride solution for 10 min and then dyed for 7 min by microwave
apparatus (2 450 MHz, 700 W) under optimum conditions which provide good exhaustion. Aqueous solutions of urea and sodium
chloride showed more effective than water as a padding solution for microwave heat dyeing. The type of solvent added in padding
media and its concentration significantly affects the K/S values of dyed polyester fabric. Added solvents such as n-hexane,
acetone, and dimethyl formamide were also more effective than 100% water as padding media for the microwave heat dyeing. It
is supposed that the effect of used solvents on dyeing property of polyester fabrics depends on the solubility parameter difference
between solvent and polyester fabric. 相似文献
100.
Jinhaeng Song Ju-eun Jeon Tae Hyung Won Chung J. Sim Dong-Chan Oh Ki-Bong Oh Jongheon Shin 《Marine drugs》2014,12(5):2760-2770
Two new peptides, chujamides A (1) and B (2), were isolated from the marine sponge Suberites waedoensis, which was collected from Korean waters. Based upon the results of the combined spectroscopic analyses, the structures of these compounds were determined to be proline-riched and cyclic cystine bridged dodeca- and undecapeptides. The absolute configurations of all amino acid residues were determined to be l by advanced Marfey’s analysis. The new compounds exhibited weak cytotoxicities against A549 and K562 cell-lines, and compound 2 also demonstrated moderate inhibitory activity against Na+/K+-ATPase. 相似文献