卵磷脂 (PC)脂质体诱发的乳液凝集举动(英文)

用光散射、荧光漏出法、表面张力、电气泳动等方法研究了添加卵磷脂 (PC)脂质体后的十六烷乳液油滴的凝集举动。调查了 3个可变因子 :①体系中LaCl3 的浓度变化 ;②脂质体的浓度 ;③脂质体的大小。实验结果表明 :在吸附的初级阶段 ,脂质体在油滴表面上将保持它的球状结构 ,之后将缓慢破裂 ,最后在油滴表面上形成单分子膜。所以 ,在脂质体被添加后的最后阶段 ,吸附在油滴表面上的脂质体将通过粒子间的架桥反应诱发油液聚集     

The effect of the CH4 level on the morphology,microstructure, phase purity and electrochemical properties of carbon films deposited by microwave-assisted CVD from Ar-rich source gas mixtures

Carbon thin films were deposited on Si substrates by microwave-assisted chemical vapor deposition (CVD) using variable CH₄ levels in an Ar/H₂ (Ar-rich) source gas mixture. The relationship between the CH₄ concentration (0.5 to 3 vol.%) in the source gas and the resulting film morphology, microstructure, phase purity and electrochemical behavior was investigated. The H₂ level was maintained constant at 5% while the Ar level ranged from 92 to 94.5%. The films used in the electrochemical measurements were boron-doped with 2 ppm B₂H₆ while those used in the structural studies were undoped. Boron doping at this level had no detectable effect on the film morphology or microstructure. Relatively smooth ultrananocrystalline diamond (UNCD) thin films, with a nominal grain size of ca. 15 nm, were only formed at a CH₄ concentration of 1%. At the lower CH₄ concentration (0.5%), faceted microcrystalline diamond was the predominant phase formed with a grain size of ca. 0.5 µm. At the higher CH₄ concentration (2%), a diamond-like carbon film was produced with mixture of sp²-bonded carbon and UNCD. Finally, the film grown with 3% CH₄ was essentially nanocrystalline graphite. The characteristic voltammetric features of high quality diamond (low and featureless voltammetric background current, wide potential window, and weak molecular adsorption) were observed for the film grown with 1% CH_4, not the films' grown with higher CH₄ levels. The C₂ dimer level in the source gas was monitored using the Swan band optical emission intensity at 516 nm. The emission intensity and the film growth rate both increased with the CH₄ concentration in the source gas, consistent with the dimer being involved in the film growth. Importantly, C₂ appears to be involved in the growth of the different carbon microstructures including microcrystalline and ultrananocrystalline diamond, amorphous or diamond-like carbon, and nanocrystalline graphite. In summary, the morphology, microstructure, phase purity and electrochemical properties of the carbon films formed varied significantly over a narrow range of CH₄ concentrations in the Ar-rich source gas. The results have important implications for the formation of UNCD from Ar-rich source gas mixtures, and its application in electrochemistry. Characterization data by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), visible-Raman spectroscopy and electrochemical methods are presented.     

The atomic structure of disordered ion tracks in magnesium aluminate spinel

Atomic resolution transmission-electron microscopy (TEM) observations and analysis have been undertaken on magnesium aluminate spinel to understand the structure of ion tracks induced by swift heavy ions. A combination of TEM techniques, which includes high-resolution and bright-field (BF) imaging, and high angular resolution electron channeling spectroscopy (HARECXS) analysis, disclosed the atomic structure of ion tracks. Swift heavy ions induce cation disordering along the latent tracks for a widespread region of 10 nm in diameter, which is much larger than a strained region detected by BF diffraction contrast. A preferential migration of cations is induced from the tetrahedral to octahedral interstitial site at the core regions of ion tracks under a condition of higher electronic excitation of (dE/dx)_e = 35 keV/nm.     

Parallel voltage sag compensator with reduced capacitance using a boost‐type power factor correction rectifier

A new circuit of parallel‐type voltage sag compensator is proposed in this paper. The proposed voltage sag compensator can reduce the necessary capacity of the energy storage capacitor for compensation by boost‐type power factor correction rectifier charging the capacitor during a voltage sag. As a result the proposed system can reduce the size and maintenance of the apparatus. Copyright © 2004 Wiley Periodicals, Inc. This paper shows the principle and control system of the proposed circuit. Compensation characteristics were demonstrated by simulation and experiment. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 19–33, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20261     

Diallyl sulfides: Selective inhibitors of family X DNA polymerases from garlic (Allium sativum L.)

Diallyl sulfides, organosulfur compounds isolated from garlic (Allium sativum L.), selectively inhibit the activities of mammalian family X DNA polymerases (pols), such as pol β, pol λ and terminal deoxynucleotidyl transferase (TdT), in vitro. The purified fraction (i.e., Sample-A) consisted of diallyl trisulfide, diallyl tetrasulfide and diallyl pentasulfide (molecular ratio: 5.3:3:1). Commercially purchased diallyl sulfides also inhibited the activities of family X pols, and the order of their effect was as follows: Sample-A > diallyl trisulfide > diallyl disulfide > diallyl monosulfide, suggesting that the number of sulfur atoms in the compounds might play an important structural role in enzyme inhibition. The suppression of human cancer cell (promyelocytic leukaemia cell line, HL-60) growth had the same tendency as the inhibition of pol X family among the compounds. Diallyl sulfides were suggested to bind to the pol β-like region of family X pols.     

Imparting cell adhesion to poly(vinyl alcohol) hydrogel by coating with hydroxyapatite thin film

To impart good cell adhesion to poly(vinyl alcohol) hydrogel (PVA-H) as an artificial articular cartilage, hydroxyapatite thin film 300 nm thick was deposited by a pulsed laser deposition technique on PVA-H, which has virtually no cell adhesion. A cell culture method was used to study the effect of hydroxyapatite deposition on PVA-H upon cell adhesion among mouse fibroblasts. The cell adhesion of water content 33% PVA-H coated with the amorphous hydroxyapatite film showed a maximum as high as that of commonly used tissue culture dishes. This technique was also effective for improving cell adhesion, even on a higher water content (53%) PVA-H. This is a novel technique to improve the biocompatibility and attachment of PVA-H and with the underlying bone and natural cartilage.     

Effect of dispersing and stabilizing additives on rheological characteristics of the upgraded brown coal water mixture

Upgraded brown coal water mixture (UBCWM) preparation by using an Indonesian upgraded coal produced by upgraded brown coal (UBC) process, was carried out to study the effect of dispersing and stabilizing additives on rheological behavior of the UBCWM. Three kinds of anionic dispersing additives, naphthalene sulfonic formaldehyde condensate (NSF), poly (meth) acrylate (PMA) and poly styrene sulfonic acid (PSS) and three kinds of stabilizing additives, carboxyl methyl cellulose (CMC), rhansam gum (S-194) and gellan gum (S-60) were used in this study. Results indicate that the addition of NSF 0.3 wt.% together with S-194 0.01 wt.% is effective in preparing UBCWM with good slurryability and stability, based on its rheological characteristics with the apparent viscosity at shear rate of 100 s^− 1 and yield stress at zero point of shear rate. The rheological behavior of all of the UBCWM that prepared, exhibits non-Newtonian Bingham plastic. From the economical point of view, the price of S-194 is expensive. On the other hand, CMC is cheap and abundant. Therefore, the addition of CMC 0.01 wt.% together with NSF 0.3 wt.% is also effective in preparing UBCWM with good fluidity and stability.     

Effect of tilt angle on cutting regime transition in glass micromilling

Recent development in mechanical micromachining technology has increased the realization of micromachining as a feasible manufacturing process of micro-scale components including glass-based devices. It has been found that glass can be machined in a ductile regime under certain controlled cutting configurations. However, favorable ductile regime machining instead of brittle regime machining in micromilling of brittle glass is still not fully understood as a function of cutting configuration. In this study, the effect of tilt angle along the feed direction on cutting regime transition has been studied in micromilling crown glass with a micro-ball end mill. Straight glass grooves were machined in water bath by varying the tool tilt angle and the feed rate, and the resulting surface was characterized using the scanning electron microscope and the profilometer to investigate the glass cutting regime transition. In characterizing the cutting regimes in glass micromilling, rubbing, ductile machining, and brittle machining regimes are hypothesized according to the undeformed chip thickness. It is found that a crack-free glass surface can be better machined in the ductile mode using a 45° tilt angle and feed rates up to 0.32 mm/min. During each milling pass, surface roughness was found to decrease from the entry zone to the groove bottom and then increase to the exit zone regardless of the cutting regime.