Retardation of discoloration of poly(vinyl chloride) and decolorization of discolored poly(vinyl chloride) with diimide

Retardation of discoloration of poly(vinyl chloride) with diimide was studied in dimethylformamide at 130°C. with the use of p-toluenesulfonylhydrazide (PSH) as a source of diimide. A process was proposed that involved prolonging the induction periods of discoloration by inhibiting the development of conjugated polyene structure. The optimum proportion of PSH was one fourth of the poly(vinyl chloride), the best results. Furthermore, poly(vinyl chloride) discolored by thermal degradation in o-dichlorobenzene or gamma-ray irradiation under vacuum was decolorized in solution at 130°C. by addition of PSH. The decolorized poly(vinyl chloride) thus obtained was thermally stable compared with that obtained by oxidative methods.     

An experimental study on unsteady turbulent near wake of a rectangular cylinder in channel flow

 Unsteady turbulent near wake of a rectangular cylinder in channel flow has been studied experimentally with a laser Doppler velocimetry (LDV). The time-averaged and phase-averaged statistics were measured for the cylinders having various width-to-height ratios, b/h. It is shown that the turbulent intensities on the centerline of the channel have their maxima near the rear stagnation point of a recirculation region. The contours of coherent vorticity and streamline reproduce clearly the shed vortices from the cylinder observed by the flow visualization. The characteristics of the flow field, which depends on b/h, are discussed and the significant contribution of the coherent structure to the flow field is clarified. Moreover, the turbulent kinetic energy budget has been examined. Received: 19 January 1998/Accepted: 21 July 1998     

A diode-pumped, self-starting, all-solid-state self-mode-locked Cr:LiSGAF laser

In this paper, a self-starting, diode-pumped self-mode-locked Cr:LiSGAF laser, which produced a stable pulse train of 45 fs duration with about 20 mW-average power at the repeated rate of 90 MHz, was presented. Self-mode-locked operation can be obtained whether there is the semiconductor saturable absorber mirror (SESAM) in the Cr:LiSGAF laser cavity or not, and with the SESAM in the cavity, the self-mode-locked operation could self-start. The shortest pulses, as short as 38 fs, which were not very stable, were obtain with the SESAM in the cavity.     

Synthesis of carbazole‐based light‐emitting polymers incorporating 2,5‐bis(phenylethenyl)‐4‐decyloxyanisole as collateral fluorophore

The Suzuki coupling polymerization between bis(carbazole) monomer ( CzDB ) and 9,9‐dihexylfluorene‐2,7‐diboronic acid was carried out to obtain PFCz‐PEDA0 having the number‐averaged molecular weight of 7000. The absorption and emission maximum wavelengths were observed at 344 and 408 nm, respectively. The quantum yield (QY) was relatively low (0.12) because of the photo‐induced electron transfer. Subsequently, CzPEDA ‐bearing 2,5‐bis(phenylethenyl)‐4‐decyloxyanisole (PEDA) segment sandwiched with 3‐bromocarbazole units was copolymerized to give PFCz‐PEDAn (n = 05, 10, 20, 35, and 50). The content of PEDA segment in polymer could be controlled by the monomer feed ratio. In CHCl₃ solution, the absorbance at around 400 nm became larger with one isosbestic point at 370 nm, and the emission peak at 448 nm became prominent with increasing the PEDA content. The QY of polymer was increased as the PEDA content, which was a consequence of the fluorescence resonance energy transfer from carbazole‐containing chromophore (energy donor) to PEDA fluorophore (energy acceptor). In spin‐coated film, the maximum QY was obtained in PFCz‐PEDA05 having the most appropriate molar balance of energy donor and acceptor units. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8141–8148, 2008     

How much should we reweigh?

Suppose that in the final stage of manufacturing of, for instance, chemical products, there is a process in which we weigh each product using a scale to obtain its exact weight, and then mark each product with its weight. In practice, such a weighing process is not necessarily carefully checked and its associated cost is reduced as much as possible since it does not affect the product quality itself. However, the scale occasionally becomes uncalibrated, that is, inaccurate, and hence will produce inaccurate weights for individual products. Particularly when the products are very heavy, a special scale is used and only qualified persons with licenses can inspect the scale to detect its inaccuracy and adjust it. We focus on a problem of this sort and propose a stochastic model aiming to control the volume of products shipped out with inaccurate marked weights.     

Effect of bredinin on the primary culture of fetal mouse cells and adult mouse lung cells.

The effects of bredinin on the primary culture of fetal mouse cells (fetal cells) and adult mouse lung cells (lung cells) were compared. Bredinin inhibited the growth of both cells, and this inhibition was found to be caused, at least in part, by the inhibition of the S phase and/or the transition from the G1 to S phase of the cell cycle. Bredinin inhibited both DNA and RNA synthesis without affecting protein synthesis. However, the inhibitory effect of bredinin differed between the two cell lines; the fetal cells were more sensitive than the lung cells, and bredinin inhibited DNA synthesis 100 times more potently in the fetal cells. The inhibition of DNA synthesis by bredinin in the fetal cells was gradually lowered by in vitro aging of the fetal cells to a level similar to that in the lung cells. There was no difference in the rate of incorporation of bredinin into the cells between the fetal cells and the lung cells. When fetal tissue was used as an enzyme source, bredinin was converted to bredinin 5'-monophosphate (BMP), but when lung tissue was used, bredinin was not converted. This is in agreement with the finding that bredinin has selective toxicity on fetuses in vivo but is hardly toxic to adult cells, which suggests the involvement of BMP in the selective toxicity of bredinin on the fetus.     

Feasibility of using [18O2]11-dehydrothromboxane B2 as an internal standard of immunoaffinity purification followed by gas chromatography/selected ion monitoring

[1,1-18O2]11-Dehydrothromboxane B2 (11-dehydro-TXB2) was prepared by repetitive base-catalyzed hydrolysis of the lactone ring of its [1,1,11-18O3]-analogue, and evaluated for its suitability as an internal standard in gas chromatography/selected ion monitoring (GC/SIM) of 11-dehydro-TXB2. Use of the present [18O2]-analogue as an internal standard may make it a suitable candidate for specific immunoaffinity purification followed by GC/SIM.     

Photoinduced nitric oxide release from a nitrobenzene derivative in mitochondria

We report a novel NO donor (RpNO), containing a 2,6-dimethylnitrobenzene moiety for photocontrollable NO release and a rhodamine moiety for targeting to mitochondria. Photorelease of NO from RpNO in aqueous solution was confirmed by means of ESR analysis. Cellular release of NO from RpNO was confirmed with the aid of DAF-FM DA, an NO-specific fluorescence probe. RpNO was colocalized with MitoTracker Green FM, a mitochondrial stain, in HCT116 colon cancer cells and exhibited photodependent cytotoxicity. Our results indicate that RpNO is an effective NO donor for time-controlled, mitochondria-specific NO treatment.