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851.
Hsu JP Ting CC Lee DJ Tseng S Chen CJ Su A 《Journal of colloid and interface science》2007,307(1):265-271
The electrokinetic flow of an electrolyte solution through a microchannel that comprises a bundle of cylinders is investigated for the case of constant surface potential. The system under consideration is simulated by a unit cell model, and analytical expressions for the flow field and the corresponding residence time distribution under various conditions are derived. These results are readily applicable to the assessment of the performance of a microreactor such as that which comprises a bundle of optical fibers. Numerical simulations are conducted to investigate the influences of the key parameters, including the thickness of the double layer, the strength of the applied electric field, the magnitude of the applied pressure gradient, and the characteristic sizes of a microchannel, on the residence time distribution. We show that the following could result in a shorter residence time: thin double layer, strong applied electric field, large applied pressure gradient, and small number of cylinders. Based on the thickness of the double layer, criteria are proposed for whether the flow field can be treated as a laminar flow or as a plug flow, two basic limiting cases in reactor design. 相似文献
852.
Spivey AC Tseng CC Hannah JP Gripton CJ de Fraine P Parr NJ Scicinski JJ 《Chemical communications (Cambridge, England)》2007,(28):2926-2928
A new class of arylgermane derivative that participate efficiently in Pd(0)-catalysed cross-coupling reactions with aryl bromides following photochemical activation is described. 相似文献
853.
Slurry sampling electrothermal vaporization dynamic reaction cell inductively coupled plasma mass spectrometry (ETV-DRC-ICP-MS)
has been applied to determine Fe, Co, Ni, Cu, and Zn in biological samples. The influences of instrument operating conditions
and slurry preparation on the ion signals were reported. Pd was used as the modifier. The effectiveness of the ETV sample
introduction technique and dynamic reaction cell in alleviating various spectral interferences in ICP-MS analysis has been
demonstrated. This method has been applied to determine Fe, Co, Ni, Cu, and Zn in NIST SRM 1573a tomato leaves reference material
and NRCC DORM-2 dogfish muscle reference material and also real samples such as a tea and a swordfish sample purchased locally.
Since the sensitivities of the elements studied in slurry and aqueous solution were different, an analyte addition technique
was used for the determinations. The analytical results of the reference materials agreed with the certified values. The precision
between sample replicates was better than 6% for all determinations. The method detection limit estimated from analyte addition
curves was 0.01, 0.006, 0.007, 0.004, and 0.006 μg g−1 for Fe, Co, Ni, Cu, and Zn, respectively, in the original biological samples. 相似文献
854.
Hsu JP Lin SH Tseng S Su A Lee DJ Chen CJ 《Journal of colloid and interface science》2007,307(2):516-523
The ionic separation efficiency of a novel membrane module comprising an array of microchannel units is analyzed. Under the Debye-Hückel approximation, we derive a semianalytical expression for the ionic separation efficiency. Analyses reveal that the effects of the size of the microchannel, the fixed charge density in the membrane layer, and the permittivity of the membrane layer on ionic separation efficiency depend strongly on the valence type of electrolyte in treated water. Under the condition of a symmetric electrolyte, the ionic separation efficiency is found to be about unity and unresponsive to variation of system parameters. If the valence of the cation is higher than that of the anion, the ionic separation efficiency is larger than unity, and decreases to unity as the size of the microchannel increases. In contrast, if the valence of the cation is lower than that of the anion, the ionic separation efficiency is smaller than unity and increases to unity as the size of the microchannel increases. Under the latter two conditions, the effects of both fixed charge density in the membrane layer and permittivity of the membrane layer on the ionic separation efficiency are found to be reversed. 相似文献
855.
Steven Yueh-Hsiu Wu Kai-Chiang Yang Ching-Li Tseng Jung-Chih Chen Feng-Huei Lin 《Journal of nanoparticle research》2011,13(3):1139-1149
In this study, sulfide-based magnetic Fe-doped CaS nanoparticles modified with a silica layer were investigated for cancer
hyperthermia. A polyvinyl pyrrolidone polymer was used as the coupling agent. The developed nanoparticles contained 11.6 wt%
iron concentration, and their X-ray diffraction pattern was similar to those of CaS and Fe–CaS nanoparticles. The average
particle size was approximately 47.5 nm and homogeneously dispersed in aqueous solutions. The major absorption bands of silica
were observed from the FTIR spectrum. The magnetic properties and heating efficiency were also examined. The specific absorption
ratio of nanoparticles at a concentration of 10 mg/mL at 37 °C in an ethanol carrier fluid was 37.92 W/g, and the nanoparticles
would raise the temperature to over 45 °C within 15 min. A cytotoxicity analysis revealed that the nanoparticles had good
biocompatibility, which indicated that the nanoparticles did not affect cell viability. The therapeutic effects of the nanoparticles
were investigated using in vitro and animal studies. Cells seeded with nanoparticles and treated under an AC magnetic field
revealed a percentage of cytotoxicity (60%) that was significantly higher from that in other groups. In the animal study,
during a hyperthermia period of 15 days, tumor-bearing Balb/c mice that were subcutaneously injected with nanoparticles and
exposed to an AC magnetic field manifested a reduction in tumor volume. The newly developed silica-modified Fe–CaS nanoparticles
can thus be considered a promising and attractive hyperthermia thermoseed. 相似文献
856.
Chir-Jang Tsai Chun-Nan Chen Wenjea J. Tseng 《Journal of nanoparticle research》2011,13(12):6859-6868
Nickel nanoparticles with an average diameter of 90 nm have been dispersed in de-ionized water with addition of pyrogallol-poly(ethylene
glycol) polymers, hereafter termed Gallol-PEG, of different molecular weights as a surfactant. Measurement of zeta potential,
infrared spectrum, and adsorption isotherm confirms the preferential anchoring from polar end of the surfactant molecules
on the particle surface, forming a Langmuir-typed adsorption layer (adlayer) to provide an electrosteric stabilization. Concentrated
nanoparticle suspensions with a solids loading up to 40 vol.% and an apparent viscosity lower than 10 Pa s at a shear rate
of 100 s−1 have been obtained, indicating that the Gallol-PEG adsorption is effective in facilitating the suspension flow under stress.
The suspensions are yet fractal in structure with an experimentally determined fractal dimension of 2.1, revealing that a
reaction-limited cluster–cluster aggregation is operative. This weakly coagulated fractal structure stems primarily from the
shallow interparticle attraction operative over a moderate interparticle separation (~5–10 nm), and is prone to the adlayer
thickness and the molecular conformation of the surfactant. 相似文献
857.
Kuo-Hsiung Tseng Yu-Chun Chen Jing-Jong Shyue 《Journal of nanoparticle research》2011,13(5):1865-1872
This article presents an electrochemical discharge (ECD) method that consists of a combination of chemical methods and electric
arc discharges. In the method, 140 V is applied to an Ag electrode from a DC power supply. The arc-discharge between the electrodes
produces metallic silver nanoparticles and silver ions in the aqueous solution. Compared with the original arc discharge,
this ECD method creates smaller nanoparticles, prevents clumping of the nanoparticles, and shortens the production time. The
citrate ions also reduce the silver ions to silver nanoparticles. In addition, the citrate ions cap the surface of the produced
silver nanoparticles and the zeta potential increases. In this article, the weight loss of the electrodes and the reduction
of silver ions to silver nanoparticles as a function of citrate concentration and electric conductivity of the medium are
discussed. Furthermore, the properties of the colloidal silver prepared with ECD are analyzed by UV–Vis spectroscopy, dynamic
light scattering, electrophoresis light scattering, and scanning electron microscopy. Finally, a continuous production apparatus
is presented for the continuous production of colloidal silver. 相似文献
858.
Shih KC Lin CY Zhou J Chi HC Chen TS Wang CC Tseng HW Tang CY 《Journal of chemical information and modeling》2011,51(2):398-407
B-Raf is a member of the RAF family of serine/threonine kinases: it mediates cell division, differentiation, and apoptosis signals through the RAS-RAF-MAPK pathway. Thus, B-Raf is of keen interest in cancer therapy, such as melanoma. In this study, we propose the first combination approach to integrate the pharmacophore (PhModel), CoMFA, and CoMSIA models for B-Raf, and this approach could be used for screening and optimizing potential B-Raf inhibitors in silico. Ten PhModels were generated based on the HypoGen BEST algorithm with the flexible fit method and diverse inhibitor structures. Each PhModel was designated to the alignment rule and screening interface for CoMFA and CoMSIA models. Therefore, CoMFA and CoMSIA models could align and recognize diverse inhibitor structures. We used two quality validation methods to test the predication accuracy of these combination models. In the previously proposed combination approaches, they have a common factor in that the number of training set inhibitors is greater than that of testing set inhibitors. In our study, the 189 known diverse series B-Raf inhibitors, which are 7-fold the number of training set inhibitors, were used as a testing set in the partial least-squares validation. The best validation results were made by the CoMFA09 and CoMSIA09 models based on the Hypo09 alignment model. The predictive r(2)(pred) values of 0.56 and 0.56 were derived from the CoMFA09 and CoMSIA09 models, respectively. The CoMFA09 and CoMSIA09 models also had a satisfied predication accuracy of 77.78% and 80%, and the goodness of hit test score of 0.675 and 0.699, respectively. These results indicate that our combination approach could effectively identify diverse B-Raf inhibitors and predict the activity. 相似文献
859.
860.
Tseng Q Wang I Duchemin-Pelletier E Azioune A Carpi N Gao J Filhol O Piel M Théry M Balland M 《Lab on a chip》2011,11(13):2231-2240
In tissues, cell microenvironment geometry and mechanics strongly impact on cell physiology. Surface micropatterning allows the control of geometry while deformable substrates of tunable stiffness are well suited for the control of the mechanics. We developed a new method to micropattern extracellular matrix proteins on poly-acrylamide gels in order to simultaneously control cell geometry and mechanics. Microenvironment geometry and mechanics impinge on cell functions by regulating the development of intra-cellular forces. We measured these forces in micropatterned cells. Micropattern geometry was streamlined to orient forces and place cells in comparable conditions. Thereby force measurement method could be simplified and applied to large-scale experiment on chip. We applied this method to mammary epithelial cells with traction force measurements in various conditions to mimic tumoral transformation. We found that, contrary to the current view, all transformation phenotypes were not always associated to an increased level of cell contractility. 相似文献