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排序方式: 共有541条查询结果,搜索用时 15 毫秒
1.
Sungyong Kim Lingxin Chen Sangyeop Lee Gi Hun Seong Jaebum Choo Eun Kyu Lee Chil-Hwan Oh Sanghoon Lee 《Analytical sciences》2007,23(4):401-405
A rapid DNA analysis has been developed based on a fluorescence intensity change of a molecular beacon in a PDMS microfluidic channel. Recently, we reported a new analytical method of DNA hybridization involving a PDMS microfluidic sensor using fluorescence energy transfer (FRET). However, there are some limitations in its application to real DNA samples because the target DNA must be labelled with a suitable fluorescent dye. To resolve this problem, we have developed a new DNA microfluidic sensor using a molecular beacon. By monitoring the change in the restored fluorescence intensity along the channel length, it is possible to rapidly detect any hybridization of the molecular beacon to the target DNA. In this case, the target DNA does not need to be labelled. Our experimental results demonstrate that this microfluidic sensor using a molecular beacon is a promising diagnostic tool for rapid DNA hybridization analysis. 相似文献
2.
Peptides containing azaglycine located terminally or within the backbone have been prepared in the solid phase by means of an automatic synthesizer. 相似文献
3.
In this paper, we report that the phase transformation of Ni-B, Ni-P diffusion barriers deposited electrolessly on Cu, for the reason that the Ni-P layer is a more effective diffusion barrier than the Ni-B layer. The Ni3B crystallized was decomposed to Ni and B2O3 above 400 °C and the Ni3P crystallized was decomposed to Ni and P2O5 above 600 °C respectively in Ar atmosphere. Also, the Ni3B was decomposed to Ni and free B above 400 °C and the Ni3P was decomposed to Ni and free P above 600 °C respectively in H2 atmosphere. The decomposed Ni formed a solid solution with Cu. The Cu diffusion occurred above 400 °C for Ni-B layer and above 600 °C for Ni-P layer, respectively. Because the decomposition temperature of Ni-P layer is about 200 °C higher than that of Ni-B layer, the Ni-P layer is a more effective barrier for Cu than the Ni-B layer. 相似文献
4.
Yong‐Jin Kim Jin‐Woong Kim Jung‐Eun Lee Jee‐Hyun Ryu Junoh Kim Ih‐Seop Chang Kyung‐Do Suh 《Journal of polymer science. Part A, Polymer chemistry》2004,42(22):5627-5635
Mesoporous polymer microspheres with gold (Au) nanoparticles inside their pores were prepared considering their surface functionality and porosity. The Au/polymer composite microspheres prepared were characterized by transmission electron microscope (TEM), X‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) techniques. The results showed that the adsorption of Au nanoparticles could be increased by imparting the pore structure and surface‐functional groups into the supporting polymer microspheres (in this study, poly (ethylene glycol dimethacrylate‐co‐acrylonitrile) and poly (EGDMA‐co‐AN) system). Above all, from this study, it was established that the porosity of the polymer microspheres is the most important factor that determines the distribution and adsorption amount of face‐centered cubic (fcc) Au nanoparticles in the final products. Our study showed that the continuous adsorption of Au nanoparticles with the aid of the large surface area and surface interaction sites formed more favorably the Au/polymer composite microspheres. The BET measurements of Au/poly(EGDMA‐co‐AN) composite microspheres reveals that the adsorption of Au nanoparticles into the pores kept the pore structure intact and made it more porous. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5627–5635, 2004 相似文献
5.
Chemisorption of polybenzimidazole on silver and copper etched with nitric acid has been observed by surface-enhanced Raman scattering (SERS). The polymer is found to react chemically with silver, forming a complexed film on the surface. The SERS spectra show that polybenzimidazole film inhibits oxidation of the metal at high temperature, unlike chemisorbed benzimidazole, benzotriazole, and poly(4-vinyl pyridine). © 1992 John Wiley & Sons, Inc. 相似文献
6.
Chae Kyu Kim Eun Seok Song Hyung Joo Kim Chiyoung Park Young Chul Kim Jai Kyeong Kim Jae Woong Yu Chulhee Kim 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):254-263
We have synthesized conjugated dendrimer with triazine peripheries, and their luminescence properties were investigated. The dendrimers consist of dendritic triazine wedges for electron transport, distyrylbenzene core as an emitting moiety, and t‐butyl peripheral groups for good processing properties. The dendrimers have LUMO values of about ?2.7 eV possibly because of the triazine moiety with high electron affinity. Photoluminescence study indicates that energy transfer occurs from the triazine wedges to the stilbene bridge, and finally to the core chromophore units due to a cascade decrease of bandgap from the peripheral wedge to core moiety. Therefore, the emission wavelength was determined by the structure of the core unit. The energy transfer efficiency of distyrylbenzene‐cored dendrimers was about 75 and 55% for Trz‐1GD‐DSB and Trz‐2GD‐DSB, respectively. A preliminary electroluminescence property also was investigated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 254–263, 2006 相似文献
7.
Metal foils for Raman scattering were prepared by HNO_3 etching method. These foils werefound to exhibit a strong SERS effect and excellent thermal stability. SERS spectra of cystaminehave been taken to illustrate the usefulness of this sample preparation method in the studies ofchemisorption. The ring opening reactions of an epoxy compound have been observed on the topof chemisorbed cystamine on silver foils. 相似文献
8.
A novel process was developed to fabricate biodegradable polymer scaffolds for tissue engineering applications, without using organic solvents. Solvent residues in scaffolds fabricated by processes involving organic solvents may damage cells transplanted onto the scaffolds or tissue near the transplantation site. Poly(L-lactic acid) (PLLA) powder and NaCl particles in a mold were compressed and subsequently heated at 180 degrees C (near the PLLA melting temperature) for 3 min. The heat treatment caused the polymer particles to fuse and form a continuous matrix containing entrapped NaCl particles. After dissolving the NaCl salts, which served as a porogen, porous biodegradable PLLA scaffolds were formed. The scaffold porosity and pore size were controlled by adjusting the NaCl/PLLA weight ratio and the NaCl particle size. The characteristics of the scaffolds were compared to those of scaffolds fabricated using a conventional solvent casting/particulate leaching (SC/PL) process, in terms of pore structure, pore-size distribution, and mechanical properties. A scanning electron microscopic examination showed highly interconnected and open pore structures in the scaffolds fabricated using the thermal process, whereas the SC/PL process yielded scaffolds with less interconnected and closed pore structures. Mercury intrusion porosimetry revealed that the thermally produced scaffolds had a much more uniform distribution of pore sizes than the SC/PL process. The utility of the thermally produced scaffolds was demonstrated by engineering cartilaginous tissues in vivo. In summary, the thermal process developed in this study yields tissue-engineering scaffolds with more favorable characteristics, with respect to, freedom from organic solvents, pore structure, and size distribution than the SC/PL process. Moreover, the thermal process could also be used to fabricate scaffolds from polymers that are insoluble in organic solvents, such as poly(glycolic acid). Cartilage tissue regenerated from thermally produced PLLA scaffold. 相似文献
9.
Kang KR Kim JS Chung SI Park MH Kim YW Lim D Lee SY 《Experimental & molecular medicine》2002,34(6):489-495
Deoxyhypusine synthase catalyzes the first step in the posttranslational synthesis of an unusual amino acid, hypusine, in the eukaryotic translation initiation factor 5A (eIF-5A) precursor protein. We earlier observed that yeast recombinant deoxyhypusine synthase was phosphorylated by protein kinase C (PKC) in vitro (Kang and Chung, 1999) and the phosphorylation rate was synergistically increased to a 3.5-fold following treatment with phosphatidylserine (P.Ser)/diacylglycerol (DAG)/ Ca(2+), suggesting a possible involvement of PKC. We have extended study on the phosphorylation of deoxyhypusine synthase in vivo in different cell lines in order to define its role on the regulation of eIF5A in the cell. Deoxyhypusine synthase was found to be phosphorylated by endogenous kinases in CHO, NIH3T3, and chicken embryonic cells. The highest degree of phosphorylation was found in CHO cells. Moreover, phosphorylation of deoxyhypusine synthase in intact CHO cells was revealed and the expression of phosphorylated deoxyhypusine synthase was significantly diminished by diacyl ethylene glycol (DAEG), a PKC inhibitor, and enhanced by phorbol 12-myristate 13-acetate (PMA) or Ca(2+)/DAG. Endogenous PKC in CHO cell and cell lysate was able to phosphorylate deoxyhypusine synthase and this modification is enhanced by PMA or Ca(2+) plus DAG. Close association of PKC with deoxyhypusine synthase in the CHO cells was evident in the immune coprecipitation and was PMA-, and Ca(2+)/phospholipid dependent. These results suggest that phosphorylation of deoxyhypusine synthase was PKC-dependent cellular event and open a path for possible regulation in the interaction with eIF5A precursor for hypusine synthesis. 相似文献
10.
A sequential injection analysis (SIA) system was developed to monitor the concentration of l-cysteine in biological processes on-line. It is based on the redox reaction of l-cysteine with iron(III) in the presence of 1,10-phenanthroline (phen) and the detection of the red-iron(II)-phen complex with a spectrophotometry. The system was fully automated using software written in the LabVIEW™ development environment. A number of system variables such as the flow rate of the carrier buffer solution, the volume ratio of the sample to the reagents, and the reaction coil length, etc., were evaluated to increase the sensitivity and performance of the SIA system. Under partially optimized operating conditions the performance of the SIA system was linear up to a concentration of l-cysteine of 1 mM (R2 = 0.998) with a detection limit of 0.005 mM and a sample frequency of 15 hr−1. The SIA system was employed to monitor the concentration of l-cysteine on-line in a continuously stirred reactor and a fermentation process of Saccharomyces cerevisiae. The on-line monitored data were in good agreement with the off-line data measured by a HPLC with a fluorescence detector (n = 15, R2 = 09899). 相似文献