Enhancement of angiotensin I converting enzyme inhibitory activity and improvement of the emulsifying and foaming properties of corn gluten hydrolysate using ultrafiltration membranes

In this study, we attempted to enhance angiotensin I converting enzyme (ACE) inhibitory activity using an ultrafiltration (UF) membrane and to improve the emulsifying and foaming properties of fractions. ACE inhibitory activities of the corn gluten hydrolysate prepared by Flavourzyme had the same trend as protein contents and the IC₅₀ value was 0.18 mg solid after 8 h hydrolysis. The hydrolysate was separated by using two kinds of UF membrane (10 and 5 kDa cut-off membranes) and three fractions, >10 kDa, 5–10 kDa, and <5 kDa, were obtained. The yields of these three fractions were 58.3%, 27.2% and 14.5% as dry matter, respectively. The IC₅₀ value (the concentration of ACE inhibitor required to inhibit 50% of the ACE activity under specific conditions) of the <5 kDa fraction was 0.05 mg solid and was approximately fourfold that of the original, 5–10, and >10 kDa fractions. The average hydrophobicity of the <5 kDa fraction was slightly lower than that of the others according to the hydrophobicity index of Nozaki and Tanford, but according to the Krigbaum and Meirovitch index, that of the <5 kDa fraction was slightly higher than those of the others, showing there might be no significant differences among the fractions. The emulsifying activity and emulsion stability in the <5 kDa fraction was higher than those in the other fractions. Two fractions, <5 kDa and >10 kDa, showed poor foaming capacity at below pH 6.0. The foam stabilities of two fractions (<5 kDa and >10 kDa) increased with increasing pH, but that of 5–10 kDa decreased with increasing pH. The UF treatment was an effective method for the enhancement of ACE inhibitory activity with improvement of functional properties.     

Dynamic mechanical properties of polyimide/poly(silsesquioxane)‐like hybrid films

Polyimide/poly(silsesquioxane)‐like (PI/PSSQ‐like) films have three‐dimensional structure with linear PI blocks and a crosslinked PSSQ‐like structure. They have higher thermal stability and char yields than pure PI from 4,4′‐diaminodiphenyl ether and 3, 3′‐oxydiphthalic anhydride (ODPA). In a series of X‐PIS [PI modified with p‐aminophenyltrimethoxysilane (APTS), where X is the molecular weight of each PI block] hybrid films, decreasing the PI block chain length enhances the storage modulus, tensile modulus, and glass‐transition temperature (T_g) but reduces the α‐relaxation damping peak intensity, density, and elongation. The change in the former three properties may be caused by an increase in the crosslinking density and rigidity of the network structure. The changes in the next two properties are caused by an increase in the free volume or the PI interblock separation and decreases in the interblock PI chain interaction. The change in the last property (i.e., a decrease in elongation) is related to the increase in the rigidity of the network structure. The activation energy of the α transition depends on the chain length of the PI block. A maximum value is reached at the chain length of 10,000 because of two different factors: crosslinking density and free volume. In a series of X‐PIS‐y‐PTS [X‐PIS modified with phenyltrimethoxysilane (PTS), where y is the weight‐ratio percentage of PTS to APTS–polyamic acid] films with a constant PI block length, the storage modulus, tensile modulus, T_g, density, and α‐relaxation damping peak intensity decrease with the PTS content. This could be because of the increase of the PSSQ‐like domain size with the PTS content, which leads to the introduction of more free volume or interblock separation and to a decrease in the interblock chain interaction force. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2500–2516, 2001     

Energy level alignment in N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB)/hexadecafluoro copper phthalocyanine (F16CuPc)/Au and NPB/CuPc/Au heterojunction

The interfacial electronic structures of N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB)/hexadecafluoro copper phthalocyanine (F₁₆CuPc)/Au and NPB/copper phthalocyanine (CuPc)/Au were investigated by in situ X-ray and ultraviolet photoelectron spectroscopy to study the hole-injection barrier depending on the ionization energy of hole-injection layer materials. Although the measured ionization energy of F₁₆CuPc (6.30 eV) was much higher than that of CuPc (5.15 eV), the difference in the barrier heights of the two different films was relatively marginal (0.27 eV) due to the formation of interface dipole caused by the charge redistribution. We confirmed that the interface dipole of the buffer layer (CuPc and F₁₆CuPc) pushed down the core levels as well as the valence levels of the top organic layer (NPB) in the NPB/F₁₆CuPc/Au and NPB/CuPc/Au heterojunction.     

A quantitative measurement of LCD and PDP TVs for human visual preference and fatigue

This study was conducted by subjective and objective measurement, to clarify the complex relationships among human visual preference and fatigue of major Flat Panel Display TVs with related physical and physiological factors. In the subjective measurement, comparison tests with 24 subjects were conducted and the semantic differential method with factor analysis was carried out for six TVs with different room luminance and length of watching time. The comparison test yielded identification of the most preferable display, which showed little connection with the TV luminance for any length of watching time and room luminance. From the statistical factor analysis of semantic differential method, significant factors were extracted for describing human visual preference. In the objective measurement, the eye motion tracking camera was used to detect the eye response and thus generated physiological data corroborated the significant factors extracted from the subjective measurement. This study allows the human perceptual preference and fatigue of electronic displays to be quantitatively measured with psychological and physiological factors and will tell which parameters are significant and guide the manufacturer in making the optimum TVs.     

Elucidation of the role of lithium iodide as an additive for the liquid-based synthesis of Li7P2S8I solid electrolyte

Liquid-phase synthesis for a sulfide-based solid electrolyte has been widely studied due to its great advantage of being a simpler and more cost-effective method compared with the conventional solid-phase synthesis, even it could induce homogeneous reactions in the solution. However, the physically and chemically stable phosphorus pentasulfide (P₂S₅) is barely soluble in various solvents; this has been a major problem for achieving a pure solution-phase dissolving solid electrolyte. Therefore, exploring an effective additive for liquid-phase synthesis would be worthwhile and could potentially lead to the discovery of new chemicals to produce qualified solid electrolytes. In this paper, lithium iodide's (LiI) dual role as a strong nucleophile as well as a major reactant source for producing Li₇P₂S₈I is first investigated. The nucleophilic additive of LiI has been proven to break the P-S bonds of P₂S₅, driving the insoluble P₂S₅ to become the soluble intermediate complex. Also, it is demonstrated that controlling the reaction times between the LiI and the P₂S₅ is key to achieving solution-based synthesis, and the role of LiI is investigated by conducting bonding analysis.     

Fabrication and radio frequency characterization of carbon nanotube field effect transistor: evidence of quantum capacitance

We fabricated an radio frequency (RF) carbon nanotube field effect transistor (CNTFET) whose electrode shapes were standard RF designed ground-signal-ground (GSG)-type pads. The S-parameters measured from our RF CNTFET in the frequency range up to 6 GHz were fitted with an RF equivalent circuit, and the extracted gate capacitance was shown to be the capacitance value of the series combination of the electrostatic capacitance and the quantum capacitance. The effect of the channel resistance and the kinetic inductance was also discussed.     

Performance evaluation of DS-CDMA system with M-ary orthogonalsignaling

The effects of signature sequence on the performance of direct-sequence code-division multiple-access (DS-CDMA) systems employing Walsh M-ary orthogonal signaling are considered. The mean-squared value of multiple access interference (MAI) is derived by treating the signature sequence as deterministic. The numerical results show that Walsh orthogonal signaling changes the original properties of signature sequences, and a different choice of signature sequence results in significant performance difference. These results can be used as guides in selecting signature sequences for systems that employ Walsh M-ary orthogonal signaling     

Synthesis of crystalline polyimide film by ionized cluster-beam deposition

Polyimide thin films were deposited by the ionized cluster-beam deposition technique. Imidization and crystallization of polyimide films were investigated using transmission electron microscopy and Fourier transform infrared spectroscopy. Polyimide films deposited under optimum conditions showed a maximum imidization and good crystal structure, which is superior to that of films fabricated by other techniques.     

The PTEN/MMAC1 tumor suppressor phosphatase functions as a negative regulator of the phosphoinositide 3-kinase/Akt pathway

The PTEN/MMAC1 phosphatase is a tumor suppressor gene implicated in a wide range of human cancers. Here we provide biochemical and functional evidence that PTEN/MMAC1 acts a negative regulator of the phosphoinositide 3-kinase (PI3-kinase)/Akt pathway. PTEN/MMAC1 impairs activation of endogenous Akt in cells and inhibits phosphorylation of 4E-BP1, a downstream target of the PI3-kinase/Akt pathway involved in protein translation, whereas a catalytically inactive, dominant negative PTEN/MMAC1 mutant enhances 4E-BP1 phosphorylation. In addition, PTEN/MMAC1 represses gene expression in a manner that is rescued by Akt but not PI3-kinase. Finally, higher levels of Akt activation are observed in human prostate cancer cell lines and xenografts lacking PTEN/MMAC1 expression when compared with PTEN/MMAC1-positive prostate tumors or normal prostate tissue. Because constitutive activation of either PI3-kinase or Akt is known to induce cellular transformation, an increase in the activation of this pathway caused by mutations in PTEN/MMAC1 provides a potential mechanism for its tumor suppressor function.     

A driving method for high-speed addressing in an AC PDP using priming effect

A novel driving method is proposed to reduce the addressing time in an ac plasma display panel. In this method, priming discharges are used to achieve high-speed addressing without adding an auxiliary electrode. Some of the scan lines were used to provide the priming particles for the reduction of the address discharge time lag (t/sub d/) in the adjacent scan lines. The number of priming electrodes was optimized and two different types of priming discharge were tested in order to reduce the inherent light output caused by the priming discharges. In the panel experiment, the t/sub d/ was reduced to one half of that of the conventional method when the priming particles were provided and the background luminance was reduced from 4.97 to 2.94 cd/m/sup 2/ through the reduction of the number of priming electrodes, and further, by changing the type of the priming discharge while the peak luminance could be improved more than twice by allocating the saved-time-to-display period, which in turn, resulted in a higher contrast ratio.