Regulation of neurite outgrowth by intermittent irradiation of visible light

The effect of neurite outgrowth of PC12 cells on collagen-coated glass plates under intermittent light irradiation at 525 nm and 0.4 mW/cm2 of intensity was investigated. Neurite outgrowth of PC12 cells was significantly suppressed when PC12 cells were cultivated under intermittent light irradiation with a total irradiation time of more than 2 min/h. No temperature increase was observed in the culture medium under either continuous or intermittent light irradiation. Therefore, suppression of neurite outgrowth under light irradiation was not due to the increase of temperature in the culture medium, but rather the effect of light on the PC12 cells, especially the signal transmittance of light to PC12 cells. The light irradiation interval also affected the neurite outgrowth of PC12 cells when the total irradiation time was constant. A high extension ratio of neurite outgrowth was observed under a long time interval of nonirradiation between light irradiations (1 min of irradiation every hour) as compared with frequent light irradiation intervals (5 s of irradiation every 5 min) with the same total irradiation period per hour. The neurite outgrowth ratio was thought to be dependent on the light intensity, the total time of light irradiation in the intermittent light irradiation, and the interval of light irradiation in the intermittent light irradiation.     

Efficient emission from charge recombination during the pulse radiolysis of electrochemical luminescent substituted quinolines with donor-acceptor character

Efficient emission from various donor-acceptor quinolines with an ethynyl linkage (PnQ), which are known as efficient electrogenerated chemiluminescent molecules, was observed with time-resolved fluorescence measurement during the pulse radiolysis in benzene. On the basis of the transient absorption and emission measurements, and steady-state measurements, the formation of PnQ in the singlet excited state can be interpreted by charge recombination between the PnQ radical cation and the PnQ radical anion which are generated initially from the radiolytic reaction in benzene. The strong electronic coupling between the donor and acceptor through conjugation is responsible for the efficient emission during the pulse radiolysis of PnQ in benzene. It is suggested that the positive and negative charges are localized on the donor and acceptor moieties in the radical cation and anion, respectively. This mechanism is reasonably explained by the relationship between the annihilation enthalpy changes and singlet excitation energies of PnQ. The formation of the intramolecular charge transfer state is assumed for PnQ in the singlet excited state with a strong electron donating substituent. The emission from PnQ is suggested to originate from PnQ in the singlet excited state formed from the charge recombination between the PnQ radical cation and the PnQ radical anion during the pulse radiolysis. This is strong evidence for the efficient electrogenerated chemiluminescence of PnQ.     

Evaluation of the dynamic properties of polymer latex particles interacting with quartz interface by evanescent wave dynamic light scattering

The diffusion behavior of polymer latex particles in dispersion near the quartz interface has been estimated by evanescent wave dynamic light scattering (EVDLS) technique. The diffusion coefficient of the particles was measured as a function of the distance between the particle and interface. The apparent diffusion coefficient estimated by EVDLS was small for particles near the interface and increased upon increasing the distance from the interface, and then saturated at a certain value which is close to the value expected for free-motion. The range of the distance over which diffusion was affected by interaction with the interface depended on the added salt concentration. This means that the diffusion of the particle is influenced by an electrostatic interaction between the particle and quartz interface in addition to the hydrodynamic effect near the wall. This range was found to be more than 800?nm at 0?M salt condition but about 400?nm at 10^-4 and 10^-3?M salt conditions. Hence it is appropriate to say that the hydrodynamic effect reaches up to 400?nm and the electrostatic effect is longer ranged, more than 800?nm, for the system studied here. The EVDLS technique is a very powerful tool for quantitative estimations of the dynamic behavior of the particle near the interface and for estimation of the range where the wall effect is dominant. EVDLS will give us an answer to the question of “where is the ‘interface’ and where is the ‘bulk’?”.     

Preparation of polysaccharide–polymethacrylate hybrid materials by radical polymerization of cationic methacrylate monomer in the presence of anionic polysaccharide

This article describes preparation of polysaccharide–polymethacrylate hybrid materials by means of free‐radical polymerization of a cationic methacrylate monomer in the presence of anionic polysaccharides. In particular, synthesis of the hybrid material composed of carboxymethyl cellulose (CMC) and a cationic polymethacrylate, i.e. poly(2‐aminoethyl methacrylate) is disclosed. The formation of the materials was achieved by radical polymerization of 2‐aminoethyl methacrylate hydrochloride (AEMA‐HCl) in aqueous solution of CMC. The insoluble material was formed and the structure was determined by the IR spectra and elemental analysis to be composed of CMC and polymethacrylate. Thermal analyses such as thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were performed to confirm the network structure of the material. The dehydrative amidation occurred by heating the material at 200°C, giving rise to the new hybrid material hybridized by the amide linkages. Copyright © 2007 John Wiley & Sons, Ltd.     

Formation Behavior and Optical Properties of Transparent Inorganic-Organic Hybrids Prepared from Metal Alkoxides and Polydimethylsiloxane

The formation behavior of the transparent inorganic-organic hybrids prepared from silanol-terminated polydimethylsiloxane (PDMS) and metal alkoxides of Al (III), Ti (IV), Zr (IV), Nb (V) and Ta (V) chemically modified with ethyl acetoacetate (EAcAc) has been investigated. EAcAc bonded to metal alkoxides remained in hydrolyzed solutions and gels to prevent the rapid growth of large inorganic particles. It is speculated that extremely small inorganic clusters are dispersed uniformly in PDMS, resulting in the transparent hybrids. The upper limit of M(OR)_n/PDMS ratio to obtain transparent hybrids was influenced by the inorganic source. As the number of remaining alkoxy groups in the modified alkoxide M(OR)_{n – x}(EAcAc)_x increased, the fabrication of transparent hybrids became difficult. The refractive index depended on the inorganic sources reflecting the difference in polarizability of the incorporated metallic ion and the molar volume of the hybrid. The refractive index increased in the order Al (III) < Zr (IV) Ti (IV) < Ta(V) Nb (V).     

Extraction behavior of divalent first row transition metal ions with N,N'-bis(2-hydroxyphenylmethyl)-N,N'-bis(2-pyridylmethyl)-1,2-ethanediamine and its derivatives

For the fundamental study on the development of novel extractants, extraction behavior of divalent first row transition metals such as manganese, nickel, copper and zinc was studied with using N,N'-bis(2-hydroxyphenylmethyl)-N,N'-bis(2-pyridylmethyl)-1,2-ethanediamine (H(2)bbpen) and its derivatives as extractants. From the numerical analysis of the intricate extraction behavior of the metals, it was found that they were extracted into chloroform not only as uncharged chelate complexes but also as ion-pairs of charged complexes with a counter anion in aqueous solution. In other words, these ligands seemed to act not only as divalent hexadentate extractants but also as monovalent tri- or tetra dentate ligands, forming positively charged complexes. Furthermore, the order of the extractabilities between the metals did not coincide with the Irving-Williams series of stability because of the 'cavity size' in the ligands and the structural rigidity of them.     

Analysis of thiamine in dried yeast by high-performance liquid chromatography and high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry

Summary High-performance liquid chromatography (HPLC) and high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (HPLC/APCI-MS) have been applied to the analysis of thiamine in dried yeast. Thiamine was extracted from dried yeast with isobutanol containing sodium 1-octanesulfonate as an ion-pairing agent and determined by HPLC on a reversed phase ODS column with UV detection at 254 nm. Response was linear in the range 25–300 μg/g of thiamine in dried yeast with a coefficient of variation in the reproducibility of 8.0%. Thiamine was recovered in good yield (109.2%, n=5). Identification of the thiamine peak was obtained by the mass spectrum using the HPLC/APCI-MS system. The utility of the selected ion monitoring technique using the HPLC/APCI-MS was also investigated. The results obtained by this method are in good agreement with those obtained by the thiochrome method [1].     

Syntheses and spectral properties of 2,3,7,8-tetracyano-5,10-dihydrodipyrazino[2,3-b:2′,3′-e]pyrazine

Base catalized intermolecular cyclization of 2-amino-3-chloro-5,6-dicyanopyrazines gave 5,10-disubsti-tuted-2,3,7,8-tetracyano-5,10-dihydrodipyrazino[2,3-b:2′,3′-c]pyrazines 11–20. These compounds have rather small molecular size but have strong intramolecular charge-transfer chromophoric system. They have strong fluorescence in solution and some have fluorescence even in the solid state which are very important to evaluate their electroluminescence property as an emitter for electroluminescence devices. The physical, structural, and electronic properties of these new 2,3,7,8-tetracyano-5,10-dihy-drodipyrazino[2,3-b:2′3′-e]pyrazines were studied using uv-visible spectroscopy and the Pariser-Parr-Pople molecular orbital calculation method.     

Relativistic Gaussian basis sets for radon through plutonium

Summary Relativistic Gaussian basis sets of neutral atoms Rn-Pu and ions Th⁺⁴, U⁺³ and Pu⁺³ in the configurations of average energies are presented. The exponent parameters of the basis sets are determined by least-squares fitting to the numerical Dirac-Fock wave functions. The total energies obtained are within 0.155 a.u. of the Dirac-Fock limits and the qualities of the basis sets are between double-zeta and triple-zeta in the valence parts. Using the exponent parameters the Breit interaction energies have been calculated by perturbation theory and the self-consistent field treatment.     

Multi-way PLS modeling of structure–activity data by incorporating electrostatic and lipophilic potentials on molecular surface

We devised and elaborated a surface-based three-dimensional-quantitative structure–activity relationship (3D-QSAR) method, which had been proposed in the previous study. This approach can be applied to more general case where both the electrostatic and lipophilic potentials on molecular surface simultaneously change. The 3D coordinates of all sampling points on molecular surface are projected into a 2D map by Kohonen neural network (KNN). Each node in the map is coded by the associated molecular electrostatic potential (MEP) or molecular lipophilic potential (MLP) values. The electrostatic and lipophilic KNN maps are generated for each compound and the four-way array is constructed by collecting two KNN maps of all samples. The correlation between four-way array and biological activity is examined by four-way partial least-squares (PLS). For validation, the structure–activity data of estrogen receptor antagonists was investigated. The four-way PLS model gave the high statistics at calibration and validation stages. The coefficients of the four-way PLS model back-projected on molecular surface had a reasonable 3D distribution and it was nicely consistent with active site of the estrogen receptor which was recently made clear by X-ray crystallography.