Diffusion of unreacted monomers detected by ATR FTIR spectroscopy in a photosensitive printing plate after the photoreaction

A water‐developable flexographic printing plate consisting of poly(acrylonitrile‐co‐butadiene), polybutadiene, and carboxylated polyurethane as a polymer matrix, hexanediol dimethacrylate and polybutadiene diacrylate as reactive monomers, and benzildimethylketal as a photoinitiator was prepared and its photoreaction followed by structural change caused by the diffusion of unreacted monomers was characterized. Analysis combined ¹³C‐NMR and attenuated total reflection (ATR) FTIR showed the photoreaction occurred predominantly at the surface of exposure to the light at first, and then the reaction proceeded to the direction of the opposite surface with an increase in the exposure time. Diffusion of unreacted monomers after the photoreaction from the unexposed side to the exposed side was monitored by ATR FTIR. The diffusivity of unreacted monomers was dependent on the extent of photoreaction in the plate and the molecular weight of diffusing monomers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2903–2907, 2004     

Evidence for an initiation site for hen lysozyme folding from the reduced form using its dissected peptide fragments

We prepared two dissected fragments of hen lysozyme and examinedwhether or not these two fragments associated to form a native-likestructure. One (Fragment I) is the peptide fragment Asn59–homoserine-105containing Cys64–Cys80 and Cys76–Cys94. The other(Fragment II) is the peptide fragment Lys1–homoserine-58connected by two disulfide bridges, Cys6–Cys127 and Cys30–Cys115,to the peptide fragment Asn106–Leu129. It was found thatthe Fragment I immobilized in the cuvette formed an equimolarcomplex with Fragment II (K_d = 3.3x10^–4 M at pH 8 and25°C) by means of surface plasmon resonance. Moreover, fromanalyses by circular dichroism spectroscopy and ion-exchangechromatography of the mixture of Fragments I and II at pH 8under non-reducing conditions, it was suggested that these fragmentsassociated to give the native-like structure. However, the mutantFragment I in which Cys64–Cys80 and Cys76–Cys94are lacking owing to the mutation of Cys to Ala, or the mutantfragment in which Trp62 is mutated to Gly, did not form thenative-like species with Fragment II, because the mutant FragmentI derived from mutant lysozymes had no local conformation dueto mutations. Considering our previous results where the preferentialoxidation of two inside disulfide bonds, Cys64–Cys80 andCys76–Cys94, occurred in the refolding of the fully reducedFragment I, we suggest that the peptide region correspondingto Fragment I is an initiation site for hen lysozyme folding.     

Comparative field study on precipitation, throughfall, stemflow, fog water, and atmospheric aerosol and gases at urban and rural sites in Japan

Precipitation collected by a wet-only sampler (WP), precipitation collected by a filtering-type bulk sampler (BP), throughfall (TF), stemflow (SF), fog water (FW), and atmospheric aerosol and gases were collected at two sites with different site classifications: an urban site (Mt. Rokko) and a rural site (Mt. Awaga) to investigate canopy-atmosphere interactions and to study the chemistry of precipitation in forested areas located in different atmospheric conditions. Compared to those at the rural site, the monthly volume-weighted pH values at the urban site were not significantly (p>0.05) different for WP, higher (p<0.05) for BP, not significantly (p> 0.05) different for TF, lower (p<0.01) for SF, and lower (p<0.01) for FW. The order of mean pH values at the urban site was FW相似文献   

Locational disadvantage of the hub

We show how spatial evolution is different between the two representative models of economic geography: [Krugman 99:483–499, 1991] and [Ottaviano et al. 43:409–436, 2002]. We analyze the impacts of falling transport costs on the spatial distribution of economic activities and welfare for a network economy consisting of three regions located on a line. It is normally considered that a hub city, i.e., a central region, always has locational advantage and manufacturing workers gain from trade. This is true in the former model, but not in the latter when markets are opened up to trade. This is because the price competition is so keen in the central region that the manufacturing sector moves to the peripheral regions, which aggravates the social welfare. We then show that when goods are close substitutes and share of manufacturing is of an intermediate level, the manufacturing activities completely disappear from the central region leading to a full agglomeration in one peripheral region.

Protein Sensing Device with Multi-Recognition Ability Composed of Self-Organized Glycopeptide Bundle

We designed and synthesized amphiphilic glycopeptides with glucose or galactose at the C-terminals. We observed the protein-induced structural changes of the amphiphilic glycopeptide assembly in the lipid bilayer membrane using transmission electron microscopy (TEM) and Fourier transform infrared reflection-absorption spectra (FTIR-RAS) measurements. The glycopeptides re-arranged to form a bundle that acted as an ion channel due to the interaction among the target protein and the terminal sugar groups of the glycopeptides. The bundle in the lipid bilayer membrane was fixed on a gold-deposited quartz crystal microbalance (QCM) electrode by the membrane fusion method. The protein-induced re-arrangement of the terminal sugar groups formed a binding site that acted as a receptor, and the re-binding of the target protein to the binding site induced the closing of the channel. We monitored the detection of target proteins by the changes of the electrochemical properties of the membrane. The response current of the membrane induced by the target protein recognition was expressed by an equivalent circuit consisting of resistors and capacitors when a triangular voltage was applied. We used peanut lectin (PNA) and concanavalin A (ConA) as target proteins. The sensing membrane induced by PNA shows the specific response to PNA, and the ConA-induced membrane responded selectively to ConA. Furthermore, PNA-induced sensing membranes showed relatively low recognition ability for lectin from Ricinus Agglutinin (RCA120) and mushroom lectin (ABA), which have galactose binding sites. The protein-induced self-organization formed the spatial arrangement of the sugar chains specific to the binding site of the target protein. These findings demonstrate the possibility of fabricating a sensing device with multi-recognition ability that can recognize proteins even if the structure is unknown, by the protein-induced self-organization process.     

Ionic salt permeability through phase‐separated membranes composed of amphoteric polymers

Amphoteric copolymers composed of hydrophilic poly(dimethyl acrylamide) and hydrophobic poly(dimethyl siloxane) formed phase‐separated membranes. The hydrophilic and hydrophobic components formed continuous phase‐separated domains in the membranes. The hydrated poly(dimethyl acrylamide) domains formed membrane‐spanning pathways, which permitted an ionic salt to permeate the membranes. The permeability of the ionic salt through the amphoteric copolymer membranes was studied. On the basis of the results, the mechanism of salt transport could be explained by the free‐volume theory, which was used for the analysis of diffusive transport in the hydrated, homogeneous membranes. The diffusion coefficient of the ionic salt increased exponentially as the volume ratio of the hydrophilic polymer to water [(1 − H)/H, where H is the degree of hydration] decreased in the membrane. It was possible to postulate that the diffusion of the ionic salt through the membranes was dependent on the free‐volume fractions of water and hydrophilic poly(dimethyl acrylamide) domains in the membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Determination of vedaprofen in livestock products and seafoods by liquid chromatography-tandem mass spectrometry

A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the trace residue determination of vedaprofen (VPF) in livestock products and seafoods. VPF was extracted from each sample with acidified acetone, and the crude extract was re-extracted with ethyl acetate and NaCl solution. Clean-up was performed using a weak anion exchange cartridge (Bond Elut DEA). The LC separation was performed on a C18 column using acetonitrile-0.0025 mol/L formic acid (3 : 2) as the mobile phase and MS was run in the negative ion electrospray ionization mode. The calibration curve was linear in the range of 0.001-0.1 μg/mL VPF. The mean recoveries from equine muscle, cattle muscle, cattle liver, cattle fat, salmon, eel, corbicula, milk, egg and buckwheat honey were 72-94%, and the relative standard deviations (RSDs) were 1.1-2.0%. Limits of quantitation (LOQs) ranged from 0.001 to 0.007 μg/g.     

Determination of 4-hydroxycoumarin rodenticides in animal products, fishery products, and honey by liquid chromatography-tandem mass spectrometry

A sensitive and selective method for the determination of 4-hydroxycoumarin-type rodenticides (warfarin, coumatetralyl, bromadiolone, and brodifacoum) in animal products, fishery products, and honey was developed. 4-Hydroxycoumarin rodenticides were extracted with acidified acetone, and the crude extract was purified by liquid-liquid partitioning followed by PSA column cleanup. Gradient liquid chromatographic separation was performed by using an Inertsil ODS-4 column, with methanol and water containing ammonium acetate as the mobile phase. Detection was carried out on a tandem mass spectrometer with electrospray ionization in the negative mode. Average recoveries from bovine muscle, bovine liver, bovine fat, swine muscle, salmon, eel, freshwater clam, egg, milk, and honey spiked at 0.0005-0.001 mg/kg were in the range of 79-108%, and the relative standard deviations were 2-8%. The limits of quantitations of the developed method were 0.0005 mg/kg for brodifacoum, 0.001 mg/kg for warfarin, coumatetralyl, and bromadiolone.