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271.
Kwan Woo Kim Keun Hyung Lee Bong Seok Lee Yo Seung Ho Seung Jin Oh Hak Yong Kim 《Fibers and Polymers》2005,6(2):121-126
Semicrystalline poly(ethylene terephthalate) (cPET)/amorphous poly(ethylene terephthalate) with isophthalic acid (aPET) blends
with 100/0, 75/25, 50/50, 25/75, and 0/100 by weight ratios were dissolved in a mixture of trifluoroacetic acid (TFA)/methylene
chloride (MC) (50/50, v/v) and electrospun via the electrospinning technique. Solution properties such as solution viscosity,
surface tension and electric conductivity were determined. The solution viscosity slightly decreased as aPET content increased,
while there was no difference in surface tension with respect to aPET composition. The characteristics of the electrospun
cPET/aPET blend nonwovens were investigated in terms of their morphology, pore size and gas permeability. All these measurements
were carried out before and after heat treatment for various blend weight ratios. The average diameter of the fibers decreased
with increasing aPET composition due to the decrease in viscosity. Also, the morphology of the electrospun cPET/aPET blend
nonwovens was changed by heat treatment. The pore size and pore size distribution varied greatly from a few nanometers to
a few microns. The gas permeability after heat treatment was lower than that before heat treatment because of the change of
the morphology. 相似文献
272.
The effect of block sequence on the self-assembly of ABC-type triblock copolymers in the ordered state is investigated using
an isothermal-isobaric molecular dynamics simulation. The block sequence has an important effect on the morphology of ABC
triblock copolymers. Different morphologies are observed depending on the block sequence as well as the block composition.
The triblock copolymers with the volume fraction of 1:1:1 (f
A=f
B=f
C=0.33) show the three phase and four layered lamellar structures irrespective of the block sequence. The A32B16C32 triblock copolymer withf
B=0.2 shows a morphology in which cylinders of midblock B are formed at the interface between A and C lamellae, whereas the
morphology of triblock copolymer B16C32A32 and C32A32B16 show a cylindrical core-shell structure and a lamellar type morphology, respectively. The A20B40C20 triblock copolymer with the block B as a major component shows a tricontinuous structure, whereas both B40C20A20 and C20A20B40 triblock copolymers exhibit the lamellar structures. When the block B has larger volume fraction withf
B=0.75, the matrix is composed of block B, and other two blocks A and C form spherical domains. 相似文献
273.
274.
Hyun Sun Cho Seung Hee Chang Youn Sun Chung Ji Young Shin Sung Jin Park Eun Sun Lee Soon Kyung Hwang Jung Taek Kwon Arash Minai Tehrani Minah Woo Mi Sook Noh Huda Hanifah Hua Jin Cheng Xiong Xu Myung Haing Cho 《Journal of veterinary science (Suw?n-si, Korea)》2009,10(1):23-28
Tetrandrine (TET), a bis-benzylisoquinoline alkaloid from the root of Stephania tetrandra, is known to have anti-tumor activity in various malignant neoplasms. However, the precise mechanism by which TET inhibits tumor cell growth remains to be elucidated. The present studies were performed to characterize the potential effects of TET on phosphoinositide 3-kinase/Akt and extracellular signal-regulated kinase (ERK) pathways since these signaling pathways are known to be responsible for cell growth and survival. TET suppressed cell proliferation and induced apoptosis in A549 human lung carcinoma cells. TET treatment resulted in a down-regulation of Akt and ERK phosphorylation in both time-/concentration-dependent manners. The inhibition of ERK using PD98059 synergistically enhanced the TET-induced apoptosis of A549 cells whereas the inhibition of Akt using had a less significant effect. Taken together, our results suggest that TET: i) selectively inhibits the proliferation of lung cancer cells by blocking Akt activation and ii) increases apoptosis by inhibiting ERK. The treatment of lung cancers with TET may enhance the efficacy of chemotherapy and radiotherapy and increase the apoptotic potential of lung cancer cells. LY294002相似文献
275.
Jung Min Ryu Dong Hyun Kim Min Young Lee Sang Hun Lee Jae Hong Park Seung Pil Yun Min Woo Jang Seong Hwan Kim Gyu Jin Rho Ho Jae Han 《Journal of veterinary science (Suw?n-si, Korea)》2009,10(2):93-98
The shortage of organ donors has stimulated interest in the possibility of using animal organs for transplantation into humans. In addition, pigs are now considered to be the most likely source animals for human xenotransplantation because of their advantages over non-human primates. However, the appropriate standard values for estimations of the liver of micropigs have not been established. The determination of standard values for the micropig liver using multi-detector row computed tomography (MDCT) would help to select a suitable donor for an individual patient, determine the condition of the liver of the micropigs and help predict patient prognosis. Therefore, we determined the standard values for the livers of micropigs using MDCT. The liver parenchyma showed homogenous enhancement and had no space-occupying lesions. The total and right lobe volumes of the liver were 698.57 ± 47.81 ml and 420.14 ± 26.70 ml, which are 51.74% and 49.35% of the human liver volume, respectively. In micropigs, the percentage of liver volume to body weight was approximately 2.05%. The diameters of the common hepatic artery and proper hepatic artery were 6.24 ± 0.20 mm and 4.68 ± 0.13 mm, respectively. The hepatic vascular system of the micropigs was similar to that of humans, except for the variation in the length of the proper hepatic artery. In addition, the diameter of the portal vein was 11.27 ± 0.38 mm. In conclusion, imaging evaluation using the MDCT was a reliable method for liver evaluation and its vascular anatomy for xenotransplantation using micropigs. 相似文献
276.
Estimation of instantaneous and daily net radiation from MODIS data under clear sky conditions: a case study in East Asia 总被引:2,自引:0,他引:2
The Moderate Resolution Imaging Spectroradiometer-based net radiation (R N) model was built and applied in East Asia in 2005. Because there have hardly been simple parameterization schemes developed over a large area using remote-sensing technology, the model was aimed to present physical simplicity in complex topography at multiple spatiotemporal scales. The model successfully reproduced the instantaneous R N values obtained at four flux tower sites having individually different ecohydrology. The diurnal cycle of R N was contextually simulated using a simple sine curve to determine the daily and monthly average net radiation. The diurnal R N estimation method was proven to be a reliable model as long as accurate boundary conditions, sunrise and sunset times, for example, were obtained. The monthly average net radiation (MANR) was estimated using the diurnal patterns of the instantaneous R N. Distribution of the monthly R N demonstrated that elevation and latitude were the primary factors affecting the MANR. The proposed R N algorithm turned out to be a promising method for valuable applications in various fields due to systematic simplicity and fewer input parameters. 相似文献
277.
Kim HJ Ahn KC Ma SJ Gee SJ Hammock BD 《Journal of agricultural and food chemistry》2007,55(10):3750-3757
Pyrethroids are widely used in agriculture as insecticides. This study describes a sensitive enzyme-linked immunosorbent assay for the detection of the glucuronide conjugate of 3-phenoxybenzyl alcohol, a putative pyrethroid metabolite that may be used as a biomarker of exposure to pyrethroids. Four antisera were elicited against two different immunizing haptens. Antisera were characterized in combination with several coating haptens. The lowest IC50 value (0.5 ng/mL) was obtained with antiserum 1891 and 3-phenoxybenzoic acid-BSA conjugate as the coating antigen. Antiserum 1891 was highly selective for the target compound with an overall cross-reactivity of <0.3% to structurally related compounds. The assay sensitivity was negligibly affected by pH 4-9. A 5-fold improvement in IC50 was observed using a 10-fold concentrated phosphate-fuffered saline as the assay buffer. Compared to assays conducted in normal phosphate-fuffered saline, the maximal absorbance was almost identical. A good correlation (r 2 = 0.99 and 0.97 for urine samples A and B, respectively) was observed between spiked levels and the levels detected by the immunoassay. 相似文献