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51.
Curcumin, which is a widely used dietary pigment and spice, has been demonstrated to be an effective inhibitor of tumor promotion in mouse skin carcinogenesis. We report that curcumin induces cell shrinkage, chromatin condensation, and DNA fragmentation, characteristics of apoptosis, in immortalized mouse embryo fibroblast NIH 3T3 erb B2 oncogene-transformed NIH 3T3, mouse sarcoma S180, human colon cancer cell HT-29, human kidney cancer cell 293, and human hepatocellular carcinoma Hep G2 cells, but not in primary culture of mouse embryonic fibroblast C3H 10T1/2, rat embryonic fibroblast, and human foreskin fibroblast cells in a concentration- and time-dependent manner. Many cellular and biochemical effects of curcumin in mouse fibroblast cells have been reported, such as inhibition of protein kinase C (PKC) activity induced by phorbol 12-myristate 13-acetate treatment, inhibition of tyrosine protein kinase activity, and inhibition of arachidonic acid (AA) metabolism. Treatment of NIH 3T3 cells with the PKC inhibitor staurosporine, the tyrosine kinase inhibitor herbimycin A, and the AA metabolism inhibitor quinacrine induces apoptotic cell death. These results suggest that, in some immortalized and transformed cells, blocking the cellular signal transduction might trigger the induction of apoptosis. 相似文献
52.
Fifty-one Staphylococcus aureus strains lacking mec for which oxacillin MICs were 1 to 8 micrograms/ml were tested against oxacillin and the combination of oxacillin and clavulanic acid with the Vitek GPS-SA card, the reference broth microdilution method, and the oxacillin agar screen plate. Of the 51 strains, 44 (86%) did not grow on the oxacillin agar screen plate, broth microdilution MICs were 1 to 2 micrograms/ml, and GPS-SA card MICs were < or = 2 micrograms/ml, with the exception of 3 strains that failed to grow in the card on repeated attempts. Another seven strains did grow on the oxacillin agar screen plate. For four of the latter group of strains, oxacillin broth microdilution MICs were > 4 micrograms/ml and GPS-SA card MICs were > or = 4 micrograms/ml; for the other 3 strains, corresponding MICs were 4 and < or = 2 micrograms/ml, respectively. The GPS-SA card classified 86% of strains as oxacillin susceptible. 相似文献
53.
C.-W.Jang J.-C.Juang F.-C.Kung 《战术导弹技术》2003,(1):58-63
给出了一种GPS卡尔曼滤波的自适应方案,该方案能根据GPS导航中变化的动态来估计协方差.当增强卡尔曼滤波器时,方案可得到更精确的定位修正.此外,也可将此估计方法用于完整监测,以增强故障检测的阈值选择.采用模拟数据验证了提出方法的正确性. 相似文献
54.
An amphoteric water‐soluble copolymer, that is, polyacrylamide/(α‐N,N‐dimethyl‐N‐acryloyloxyethyl)ammonium ethanate (PAAM/DAAE) was synthesized and it showed the ability to disperse BaTiO3 (BT) particles in aqueous solutions. In this work, the effect of molecular weight of this polymer on the dispersing properties was further examined. The results indicate that the effectiveness of three polymer samples with different molecular weights in the dispersion of BT particles is P2 (Mw = 1.1 × 105) > P1 (Mw = 1.2 × 104) > P3 (Mw = 3.0 × 105). Apparently, P2 is most effective in dispersing the particles, reducing the viscosity of the suspensions, and obtaining highest green and sintered densities. This is attributed to the highest adsorption of this polymer onto BT powder, and causes strongest electrostatic and steric repulsions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 886–891, 2006 相似文献
55.
56.
This study discusses ink‐jet printing of nylon fabric with reactive dyestuff. Specifically, this paper investigates the impact of the concentration levels of pretreatment paste on fabric permeability, and examines the influence of various acid agents, hygroscopic agents and different processing conditions on colour yield. Results show that ink‐jet printing displayed excellent wet fastness in repeated wash testing. This study used four reactive dyestuffs, cyan, magenta, yellow and black, all of which achieved both wash fastness and crock fastness of grade 4. 相似文献
57.
Increasing the potency of a cytotoxin with an arginine graft 总被引:1,自引:0,他引:1
Fuchs SM Rutkoski TJ Kung VM Groeschl RT Raines RT 《Protein engineering, design & selection : PEDS》2007,20(10):505-509
Variants and homologs of bovine pancreatic ribonuclease (RNase A) can exhibit cytotoxic activity. This toxicity relies on cellular internalization of the enzyme. Residues Glu49 and Asp53 form an anionic patch on the surface of RNase A. We find that replacing these two residues with arginine does not affect catalytic activity or affinity for the cytosolic ribonuclease inhibitor (RI) protein. This 'arginine graft' does, however, increase toxicity towards human cancer cells. Appending a nonaarginine domain to this cationic variant results in an additional increase in cytotoxicity, providing one of the most cytotoxic known variants of RNase A. These findings correlate the potency of a ribonuclease with its deliverance of ribonucleolytic activity to the cytosol, and indicate a rational means to enhance the efficacy of ribonucleases and other cytotoxic proteins. 相似文献
58.
John J. Petrovic Maria I. Pena Ivar E. Reimanis Michael S. Sandlin Samuel D. Conzone H. Harriet Kung Darryl P. Butt 《Journal of the American Ceramic Society》1997,80(12):3070-3076
The mechanical behavior of MoSi2 reinforced–Si3 N4 matrix composites was investigated as a function of MoSi2 phase content, MoSi2 phase size, and amount of MgO densification aid for the Si3 N4 phase. Coarse-phase MoSi2 -Si3 N4 composites exhibited higher room-temperature fracture toughness than fine-phase composites, reaching values >8 MP·am1/2 . Composite fracture toughness levels increased at elevated temperature. Fine-phase composites were stronger and more creep resistant than coarse phase composites. Room-temperature strengths >1000 MPa and impression creep rates of ∼10−8 s−1 at 1200°C were observed. Increased MgO levels generally were deleterious to MoSi2 -Si3 N4 mechanical properties. Internal stresses due to MoSi2 and Si3 N4 thermal expansion coefficient mismatch appeared to contribute to fracture toughening in MoSi2 -Si3 N4 composites. 相似文献
59.
John J. Petrovic Maria I. Pena H. Harriett Kung 《Journal of the American Ceramic Society》1997,80(5):1111-1116
Details of the fabrication and microstructures of hot-pressed MoSi2 reinforced–Si3 N4 matrix composites were investigated as a function of MoSi2 phase size and volume fraction, and amount of MgO densification aid. No reactions were observed between MoSi2 and Si3 N4 at the fabrication temperature of 1750°C. Composite microstructures varied from particle–matrix to cermet morphologies with increasing MoSi2 phase content. The MgO densification aid was present only in the Si3 N4 phase. An amorphous glassy phase was observed at the MoSi2 –Si3 N4 phase boundaries, the extent of which decreased with decreased MgO level. No general microcracking was observed in the MoSi2 –Si3 N4 composites, despite the presence of a substantial thermal expansion mismatch between the MoSi2 and Si3 N4 phases. The critical MoSi2 particle diameter for microcracking was calculated to be 3 μm. MoSi2 particles as large as 20 μm resulted in no composite microcracking; this indicated that significant stress relief occurred in these composites, probably because of plastic deformation of the MoSi2 phase. 相似文献
60.
CY Kung SL Young HZ Chen MC Kao L Horng YT Shih CC Lin TT Lin CJ Ou 《Nanoscale research letters》2012,7(1):372
ABSTRACT: One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E2(H) mode intensity and increase of E1(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods. 相似文献