Solvent effects in phase-transfer reactions prompted by polymer-supported phosphonium salts

Solvent effects on the intrinsic activity of, the ion-exchange rate of, and the overall activity of polymer-supported phosphonium salts under tri-phase conditions were studied. The intrinsic activity of the catalysts as well as of soluble phosphonium salts was dependent only slightly on organic solvents. The exchange rate of the chloride ion in the catalysts against the acetate ion dependent on the solvents when the degree of ring substitution was ≤ 16%. With the ca. 30% ring-substituted catalysts the rate increased and hardly depended on the solvents. The overall reactivity of the catalysts for the reaction of organic halides with NaCN was a function of substrate structure and organic solvents. For alkyl halides such as bromooctane the catalysts were more reactive in good solvents such as toluene or chlorobenzene than in poor solvents such as octane. For arylalkyl halides such as benzyl chloride the catalysts exhibited the opposite effect. In poor solvents the arylalkyl halides are absorbed preferentially into the catalysts.     

Peculiar temperature dependence of the binding of methyl orange and its homologs by 2-diethylaminoethyl methacrylate-N-vinyl-2-pyrrolidone copolymers

2-Diethylaminoethyl methacrylate (DEAEMA)–N-vinyl-2-pyrrolidone (VPy) copolymers of various compositions have been synthesized. The resultant copolymers were examined for their ability to bind methyl orange and its homologs, in particular butyl orange, at 5, 15, 25, and 35°C in aqueous solutions. The amount of binding of butyl orange is much higher with the copolymers than with polyvinylpyrrolidone or with 2-hydroxyethyl methacrylate–N-vinyl-2-pyrrolidone copolymers. Introduction of only 3% of the hydrophobic DEAEMA residue increases markedly the binding affinity toward the cosolute. Maximal binding is obtained at 15°C in the temperature range measured. This peculiar temperature dependence of the extent of binding is explicable on the basis of hydrophobic effects involved in this binding. The peculiar temperature dependence disappeared in aqueous solution of NaSCN which acts as a water-structure breaker: the extent of binding changes regularly with temperature. This is interpretable only in terms of reduction of hydrophobic contribution to the binding. With propyl orange, which is a less hydrophobic cosolute than butyl orange, the peculiarity of the binding was not detected.     

Binding of butyl orange by poly(2-dimethylaminoethyl methacrylate) and copolymers of 2-dimethylaminoethyl methacrylate and N-vinyl-2-pyrrolidone: Peculiar temperature dependence of the binding

The temperature dependence of the binding of butyl orange by a homopolymer of 2-dimethylaminoethyl methacrylate (DMAEMA) and copolymers of DMAEMA and N-vinyl-2-pyrrolidone (VPy) has been examined at various pH's. The binding is very much dependent upon the temperature of the system, the pH of the binding medium, and the DMAEMA content in the polymer. In this case maximal binding is obtained at approximately 15–25° in the temperature range measured, although in most cases which have been examined, the degree of binding increases steadily with increasing temperature. This peculiar temperature dependence of the binding becomes more pronounced as the pH and the DMAEMA content are increased. The appearance of the peculiarity is discussed in terms of the pH-induced conformational changes of the polymer and the hydrophobicity of the polymer.     

The effect of charged additives on the conductivity and the thermopower in liquid selenium

The simultaneous measurements of conductivoty σ and thermopower S for liquid Se and its dilute mixtures containing Na, Tl and Cl have been performed in the temperature and pressure range up to 1500°C and 2200 bar. The addition of Na, Tl and Cl give rise to a substantial increase in σ at low temperatures. The value of S of liquid Se is large positive at low temperature. The sign of S is changed to be negative by addition of Na and Tl. By the addition of Cl the sign of S remains positive and the value increases. The effect of charged additives on the transport properties of liquid Se is discussed in connection with the change of the bonding configuration.     

Latex piezoelectric immunoassay: detection of agglutination of antibody-bearing latex using a piezoelectric quartz crystal

A method for immunoassay of CRP (C-reactive protein) was developed using a piezoelectric quartz crystal. Previous immunoassays using a piezoelectric crystal have required the formation of a thin film on the crystal, to which an antibody is affixed. The occurrence of antigen-antibody reaction increases the weight attached to the crystal surface, which causes a reduction in the oscillation frequency. In our method, the frequency reduction was observed using antibody-bearing latex without any film. One possible mechanism of the frequency change is that the crystal acts as a sensing apparatus for viscosity or density change in the solution due to aggregation of latex particles. The detection limit was almost the same as that for latex photometric immunoassay (LPIA). The present method has been designated as latex piezoelectric immunoassay (LPEIA).     

Rapid aggregation of gold nanoparticles induced by non-cross-linking DNA hybridization

To date, aggregation of DNA-functionalized gold nanoparticles by hybridization of target DNA in a cross-linking configuration has been intensively studied. Here, we report that aggregation in a non-cross-linking configuration is also possible and is even better from the viewpoint of genetic analysis because of its speed and sensitivity. In this system, 15 nm diameter gold nanoparticles functionalized with (alkanethiol)-15mer DNA are hybridized to target 15mer DNA at room temperature. At high NaCl concentration (>/=0.5 M), hybridization with complementary target DNA induces nanoparticle aggregation based on the salting-out effect. The aggregation can be detected by a colorimetric change of the colloidal solution within 3 min. Furthermore, unusual sensitivity of this system for single-base mismatch at the terminus opposite to the anchored side has been discovered. In fact, target DNA with such a kind of mismatch does not induce the colorimetric change at all, while target DNA with single-base mismatch at the middle of it cannot be discriminated from the fully complementary target. This non-cross-linking aggregation system opens up a new possibility of rapid and reliable genetic analysis.     

Electrochemical immunoassay combined with column liquid chromatography: determination of phenytoin in human serum

A new electrochemical immunoassay combined with column liquid chromatography has been developed for the determination of phenytoin in human serum. Phenytoin was labelled with the electrochemically active nitroxide, and the separation of the free labelled antigen from other electrochemically active compounds in serum was accomplished by the use of gel chromatography. Serum samples were mixed with the antibody and the labelled antigen, incubated for 90 min, and then a 100-microliter aliquot of the mixture was directly injected to the column, which was equipped with an electrochemical detector. With 10 microliter of serum, the smallest detectable concentration of phenytoin was 2 micrograms/ml.     

Effects of pressure to adhesion

Summary Strength of adhesion bond of electropolished copper plates bonded with epoxy resin and cured under high nitrogen pressure of 1–1000 kg/cm₂ within an autoclave at 90 °C and 170 °C, was measured. From the results, it was observed that up to the pressure of about 150 kg/cm² the adhesive bond strength increases with pressure, however, decreases with higher pressure above it. The increase of bond strength would be due to the promotion of flow of adhesive into the pits existing on the surface by pressure, and the decrease would be caused by remarkable rise of viscosity of adhesive with pressure. The correlation was confirmed through a theoretical analysis, using Bueche's relation concerning pressure dependency of viscosity with some assumptions.

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Zusammenfassung Die Festigkeit von adh?siven Bindungen an elektropolierten Kupferplatten mit Epoxydharz und unter hohen Stickstoffdrucken von 1–1000 kg/cm², in einem Autoklaven hei 90 und 170 °C geh?rtet, wurden gemessen. Aus den Ergebnissen folgt, da? bei Drucken bei 150 kg/cm² die Bindungsfestigkeit anw?chst, bei h?heren Drucken jedoch wieder abf?llt. Das Ansteigen der Festigkeit wird dem Hineinflie?en des Klebemittels in die Spalten an der Oberfl?che durch den Druck zugeschrieben, die Abnahme danach durch st?rkeren Anstieg der Viskosit?t des Klebstoffes mit dem Druck verursacht sein. Diese Korrelation wurde durch theoretische Analyse unter Verwendung der Beziehung vonBueche zwischen Druck und Viskosit?t und einigen weiteren Annahmen erh?rtet.

     

Alteration in the temperature-dependent content release property of thermosensitive liposomes in plasma

The effect of plasma components on the temperature-dependent content release property of thermosensitive liposomes has been described. Temperature-sensitive liposomes containing mitomycin C (MMC) were prepared from dipalmitoylphosphatidylcholine (DPPC liposomes) and a 7 : 3 mixture of DPPC and dipalmitoylophosphatidylglycerol (DPPC/DPPG liposomes). We defined in this study the difference in the content release between 38 degrees C and 44 degrees C as an index of the temperature-dependent content release efficiency (Delta% release). In the absence of rat plasma, the Delta% release of the DPPC liposomes and the DPPC/DPPG liposomes was 83% and 71%, respectively. However, when the release study was conducted with rat plasma, the Delta% release increased to about 96% for both liposomes. In addition, while the DPPC liposomes were destabilized by rat plasma below the gel-to-liquid crystalline phase transition temperature (T(m)), MMC leakage from the DPPC/DPPG liposomes below T(m) was suppressed by rat plasma. Moreover, the plasma protein binding onto lipid bilayer was concomitant with the gel-to-liquid crystalline phase transition and then enhanced the temperature-dependent release from the DPPC/DPPG liposomes. The possible mechanism of interaction between liposomes and plasma proteins, especially serum albumin, was discussed based on differential scanning calorimetry and protein binding experiments.