Search

In process industries, it is important to maintain the desired control performance in steady state because of requirement of high-quality products and energy saving. This is the main motivation in the development of a performance-driven control scheme based on the minimum variance control law. In that scheme, controller parameters are adjusted when the control performance based on the MV-Index (Minimum Variance Index) deteriorates. However, this MV-Index based tuning scheme only takes into account only controller error variance unfortunately with no regard for manipulative variable activity. To circumvent this omission, this paper describes a design of a new performance-driven control system whose control performance assessment scheme takes into account controller error variance as well as the manipulating variable variance. Furthermore, in this newly proposed scheme, controller parameters are calculated using a fictitious reference iterative tuning (FRIT) scheme which is one of the data-driven tuning scheme. The effectiveness of the proposed scheme is demonstrated by evaluation on a numerical example.

Bioshell calcium oxide (BiSCaO) is a scallop-shell powder heated at a high temperature. BiSCaO is composed mainly of calcium oxide and exhibits broad microbicidal properties. The aim of this study is to evaluate the disinfection and decontamination abilities of BiSCaO colloidal dispersions with that of commercially available bioshell calcium hydroxide (BiSCa(OH)2) following the formation of flocculants/precipitates under strongly alkaline conditions (pH 11.5&ndash, 12.2). Various concentrations of BiSCaO and BiSCa(OH)2 colloidal dispersions were prepared by mixing with Na-polyPO4 (PP) and Na-triPO4 (TP) as flocculating agents. The microbicidal activities, and the degree of flocculation/precipitation of trypan blue, albumin, chondroitin sulfate, heparin, non-anticoagulant heparin carrying polystyrene (NAC-HCPS), and low-molecular-weight heparin/protamine nanoparticles (LMWH/P NPs) were dependent on the pH, the average particle diameter, and the concentration of BiSCaO or BiSCa(OH)2 and of the phosphate compound. BiSCaO (average particle diameter: 6 &mu, m) colloidal dispersions (0.2 wt.%) containing 0.15 wt.% PP or TP exhibited substantially stronger microbicidal activity and flocculation/precipitation under strongly alkaline conditions. These results suggest that BiSCaO colloidal dispersions together with phosphate compounds have practical applicability for disinfection.

Tyrosinase is the key enzyme involved in melanogenesis. The aim of this study was to investigate the in vitro inhibitory effects of gnetin C, a resveratrol dimer isolated from melinjo (Gnetum gnemon) seeds, on tyrosinase activity and melanin biosynthesis in murine B16 cells. The inhibitory activities of gnetin C and resveratrol were shown to be almost equal against tyrosinase and melanin biosynthesis in the cells. The IC(50) values of gnetin C activity against tyrosinase and melanin biosynthesis were 7.0 and 7.6 µM, respectively, whereas resveratrol demonstrated IC(50) values of 7.2 and 7.3 µM, respectively. These results indicated that gnetin C inhibited melanogenesis, in a manner similar to that of resveratrol, by inhibiting tyrosinase and may therefore function as a new skin-whitening agent. However, the direct effects of gnetin C and resveratrol on murine tyrosinase activities were not equal. The IC(50) value of resveratrol was 10.1 µM, while gnetin C only exhibited a 25.2% enzyme inhibition at 16 µM. The IC(25) values for gnetin C and resveratrol were 15.5 and 4.0 µM, respectively. Therefore, it is suggested that the effects of gnetin C may be due to mechanisms other than the direct inhibition of tyrosinase activity.

We fabricated white polymer light-emitting diodes (PLEDs), in which the active region is doped with a low-weight molecule. The host polymer material is Poly(9,9-didodecyl-fluorenyl-2,7-yleneethylnylene) (PFO), while the guest luminescent low-weight-molecule is 4-(Dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM). The photoluminescence (PL) and electroluminescence (EL) spectra strongly depend on DCM-doping-density. However, the most suitable DCM-doping-densities for white emissions in PL and EL are slightly different. This discrepancy is caused by the difference in excitation efficiencies. The photo-excitation system for PL measurement is better than the current injection for generating carriers efficiently. Thus, the realization of the white EL signal requires the larger DCM-doping-density than that of the white PL signal. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

SUMMARY Molluscan smooth muscle can maintain tension over extended periods with little energy expenditure, a process termed catch. Catch is thought to be regulated by phosphorylation of a thick filament protein, twitchin, and involves two phosphorylation sites, D1 and D2, close to the N and C termini,respectively. This study was initiated to investigate the role of the D2 site and its phosphorylation in the catch mechanism. A peptide was constructed containing the D2 site and flanking immunoglobulin (Ig) motifs. It was shown that the dephosphorylated peptide, but not the phosphorylated form, bound to both actin and myosin. The binding site on actin was within the sequence L10 to P29. This region also binds to loop 2 of the myosin head. The dephosphorylated peptide linked myosin and F-actin and formed a trimeric complex. Electron microscopy revealed that twitchin is distributed on the surface of the thick filament with an axial periodicity of 36.25 nm and it is suggested that the D2 site aligns with the myosin heads. It is proposed that the complex formed with the dephosphorylated D2 site of twitchin, F-actin and myosin represents a component of the mechanical linkage in catch.

Tyrosinase is the key enzyme involved in melanogenesis. The aim of this study was to investigate the in vitro inhibitory effects of gnetin C, a resveratrol dimer isolated from melinjo (Gnetum gnemon) seeds, on tyrosinase activity and melanin biosynthesis in murine B16 cells. The inhibitory activities of gnetin C and resveratrol were shown to be almost equal against tyrosinase and melanin biosynthesis in the cells. The IC(50) values of gnetin C activity against tyrosinase and melanin biosynthesis were 7.0 and 7.6 µM, respectively, whereas resveratrol demonstrated IC(50) values of 7.2 and 7.3 µM, respectively. These results indicated that gnetin C inhibited melanogenesis, in a manner similar to that of resveratrol, by inhibiting tyrosinase and may therefore function as a new skin-whitening agent. However, the direct effects of gnetin C and resveratrol on murine tyrosinase activities were not equal. The IC(50) value of resveratrol was 10.1 µM, while gnetin C only exhibited a 25.2% enzyme inhibition at 16 µM. The IC(25) values for gnetin C and resveratrol were 15.5 and 4.0 µM, respectively. Therefore, it is suggested that the effects of gnetin C may be due to mechanisms other than the direct inhibition of tyrosinase activity.

Electron-impact-induced luminescence was measured for benzaldehyde at low vapor pressure. Phosphorescence bands from the zero-point level of T 1 were observed at 397.427, and 460 nm. The pressure dependence of the phosphorescence decay rate was found to be essentially the same as that obtained by optical excitation. In addition to these bands, closely spaced, weak emission bands were observed. These emissions were found to have much shorter lifetimes than the phosphorescence from the zero-point level and to be sensitive to collisional quenching. We assign the latter bands to the phosphorescence from vibrationally excited T 1 molecules.

The fluorescence peak intensity of anthracene crystals was measured as a function of the incident light intensity, using a pulsed nitrogen laser as an excitation source. Non-linear quenching of fluorescene was observed at higher excitation intensities. The phenomena are interpreted in terms of the bimolecular annihilation of singlet excitons, which takes place much faster than the present detecting system. From the exciton density at the threshold of these phenomena, the upper limit of the collision distance for the singlet exciton was determined to be 40A. The value obtained is consistent with the dipole mechanism suggested for the collision annihilation of excitons.

The previously proposed method of studying T-T energy trasfer between like molecules using isotopic mixtures was further improved and applied to an investigation of naphthalene and phenanthrene molecules. Critical transfer distances of 15 and 13 A were determined for naphthalene and phenanthrene, respectively. The present method has the advantage that it is free from the effect of S-S energy transfer.

Luminescence from acetone and acetone-d6 has been investigated at pressures of 3.4–13 mTorr under electron impact. The decay curves of both compounds are found to be composed of two or three components depending on pressure. The decay rates and time-resolved spectra have been measured for the respective components as functions of pressure, and the nature of the states responsible for these emission components is discussed in relation to triplet-state dynamics.

Electron-impact-induced phosphorescence was observed for acetophenone at pressures between 3.2 and 48 mTorr. In addition to normal phosphorescence from the T1 zero-point level, we observed phosphorescence from vibrationally excited T1 molecules at lower pressures. Collisional quenching of the triplet levels is discussed based on the pressure dependence of the phosphorescence. Excitation functions were measured for these two kinds of phosphorescence and the mechanism of triplet-state formation is discussed.

A novel method is presented to elucidate triplet–triplet energy transfer between like molecules, in which phosphorescence decay is observed for rigid solutions containing both hydrogenated and deuterated organic molecules. It is shown that a critical transfer distance is obtained from the concentration dependence of the phosphorescence decay curves.

Fragmentations of pyridazine, pyrazole, 2-pyrazoline, hydrazine, and 1,1-dimethylhydrazine were studied by means of electron-impact luminescence. Emissions of CN and NH radicals were observed, while emission of molecular nitrogen was absent. It was concluded that the cleavage of N–N bond is important in the fragmentation of these molecules.

Electron-impact-induced phosphorescence of 1-indanone was observed for the first time at low pressure. The mechanism of triplet-state formation of this molecule by electron-impact excitation was studied by measuring excitation energy dependence of the phosphorescence intensity.

Phosphorescences of benzophenone were measured at pressures between 0.4 and 2.2 Pa under electron impact. Emissions from vibrationally excited T1 molecules were observed at lower pressures. Excitation mechanism by electron impact was discussed on the basis of excitation energy dependence.

Electron-impact-induced phosphorescence of biacetyl was observed at low vapor pressures. Excitation functions and decay characteristics of the phosphorescence were measured as functions of pressure. Mechanisms of triplet formation under electron impact are discussed in terms of these results as well as previously reported electron spectroscopic data.

Electron-impact luminescence spectra were measured for cyclohexanol, acetic acid, pyridine, pyrimidine, benzonitrile, aniline, nitrobenzene, p-methoxy-nitrobenzene, 1-chlorobutane, 1-chloropentane, tetrahydrofuran and anisole. The spectra were analyzed and compared with the literature data of mass spectrometry. It was found that fragment emissions of OH(A2Σ+-X2Π), CN(B2Σ-X2Σ), NO(B2Π-X2Π) and HCl+(A2Σ-X2Π) can be used for the identification of neutral fragments of OH and H2O, HCN, NO and HCl, respectively.

Nanosecond time-resolved fluorescence spectra were measured at 77°K for pyrene and perylene crystals, and anomalous emissions which have lifetimes of ∼ 8 nsec and are difficult to be found by the usual steady excitation, were observed at the higher-wave number sides of the usual excimer emissions. From the band position and the vibrational structure, the anomalous emission was interpreted as being due to monomer defects in each crystal. The analysis of the observed rise and decay curves of the monomer defect and excimer emissions shows that the excited states of both emissions are populated independently from the band level of each crystal excited by light irradiation. The temperature dependence of the emission indicates that a thermal activation of 0.035 eV is required for the excimer formation in a perylene single crystal, while no activation energy is required for the excitation of the monomer defect.

The bimolecular annihilation of singlet excitons in pyrene, perylene, and anthracene crystals was studied by the aid of a nitrogen gas laser. The rate constant, γ, for bimolecular annihilation was estimated at 293°K to be 9×10−15 and 8×10−14 cm3 sec−1 for pyrene and perylene, respectively. The temperature dependence of γ was measured with the result that it increases with the increasing temperature for the pyrene and perylene crystals, while it is almost independent of temperature for anthracene between 77°K and 293°K. The difference in the temperature dependence of γ was attributed to the difference in the mechanism of the exciton migration of the crystals. The method developed by the present authors for studying the exciton migration based on the exciton bimolecular annihilation was compared with that obtained previously by the use of mixed crystals.

Measurements of the phosphorescences of organic compounds at low pressures are expected to offer important information concerning the photophysical nature of molecules. However, only few such measurements have been reported, possibly because optical excitations are not efficient for the formation of triplet states at low pressures. The electron-impact method, on the other hand, has been expected to have larger excitation efficiencies, even at low pressures. However, the method had not been successfully applied to phosphorescence measurements in the vapor phase until we observed phosphorescences of benzaldehyde, acetophenone, and pyrazine by electron impact. Phosphorescences of these molecules were only observable at pressures higher than 0.3 Pa. (These pressures are still "very low" from the view point of excited-state dynamics of organic molecules in the gas phase. Luminescences of organic molecules have seldom been measured at pressures lower than a few Pa.) Since electron-impact experiments are usually conducted at pressures around 10 mPa or lower, care must be taken when this method is applied to studies of phosphorescences at higher pressures.

The triplet-triplet energy transfer between like molecules was investigated for the system of quinoxaline in ethanol by using the method of optical detection of zero-field magnetic resonance at 1.4 K. The concentration dependence of the spin state population indicates that the energy transfer between quinoxaline molecules takes place at concentrations higher than about 2×10−2 mol/dm3.